What happened at Tuesday's second impeachment hearing

• Kurt Volker, the former special envoy to Ukraine, said he was unaware that efforts to pressure Ukraine to open investigations were meant to target former Vice President Joe Biden.
• Volker testified alongside Tim Morrison, a former National Security Council official who worried about a leak of the summary of the president's July 25 call with the president of Ukraine.
• Read and watch highlights of the first hearing here.
• Download the free CBS News app to stream live coverage of all the impeachment hearings.

Washington -- The former special envoy to Ukraine told lawmakers he was unaware that efforts to pressure the Ukrainian government to opening anti-corruption investigations were targeting former Vice President Joe Biden and his son Hunter, but said he would have raised objections if he knew then what he knows now.

Kurt Volker, the former special representative, and Tim Morrison, a former National Security Council official, testified before the House Intelligence Committee on Tuesday to detail their knowledge of the events at the center of the impeachment inquiry. The pair were the second set of witnesses in Tuesday's hearings, which featured two White House officials at an earlier session.

"In hindsight, I now understand that others saw the idea of investigating possible corruption involving the Ukrainian company Burisma as equivalent to investigating former Vice President Biden," Volker said, referring to the energy company that had employed Hunter Biden. "I saw them as very different -- the former being appropriate and unremarkable, the latter being unacceptable. In retrospect, I should have seen that connection differently, and had I done so, I would have raised my own objections."

Volker is one of the central players in the effort to use the prospect of a White House visit as leverage to pressure the Ukrainian government. Morrison was on the July 25 call between President Trump and Ukrainian President Volodymyr Zelensky, and told the committee in closed-door testimony that he didn't think "anything illegal was discussed."

Volker also defended Biden from accusations he acted improperly, calling him "an honorable man" and dismissing the allegations as "not credible."

"At no time was I aware of, or knowingly took part in, any effort to urge Ukraine to investigate former Vice President Biden," Volker said.

For his part, Morrison said he was not concerned by anything he heard on the July 25 call, which he heard firsthand. But he said he grew increasingly concerned about a delay in U.S. military aid to Ukraine, and said U.S. Ambassador the EU Gordon Sondland spoke directly and regularly with the president. Sondland told Ukrainian officials the delay in military aid was "likely" contingent on launching investigations.

​Schiff sets scene for hearing, which Nunes decries as a "circus"

3:37 p.m.: Schiff began his opening statement by recapping many of the events leading to this day, outlining involvement by Volker and Morrison. Republicans requested the testimony of these two officials. Schiff declined to grant a number of Republicans' requests for other witnesses, including Hunter Biden.

"I appreciate the minority's request for these two important witnesses," Schiff said.

Nunes declared the hearing is "act two of today's circus," following Tuesday morning's testimony.

The top Republican on the committee decried Democrats' decision not to allow Hunter Biden to testify.

Schiff and Nunes have both used new opening statements for each new hearing. -- Kathryn Watson

​Morrison says his fears over disclosure of call "have been realized"

3:42 p.m.: In his brief opening statement, Morrison said he is there not to determine whether Mr. Trump's decisions amount to impeachable offenses, only to lay out facts.

"Whether the conduct that is the subject of this inquiry merits impeachment is a question for the U.S. House of Representatives; I appear here today only to provide factual information based upon my knowledge and recollections of events," Morrison said.

Morrison went on to say he doesn't view any differences he and colleagues might have as "the result of an untoward purpose."

"My recollections and judgments are my own," Morrison said. "Some of my colleagues' recollections of conversations and interactions may differ from mine, but I do not view those differences as the result of an untoward purpose."

Morrison recalled how he feared the disclosure of Mr. Trump's July 25 phone call with Zelensky "would play in Washington's political climate."

"My fears have been realized," he said.

The former National Security Council official made a point that he "left the NSC completely of my own volition," a decision he says he made before he decided to testify. -- Kathryn Watson and Stefan Becket

​Volker insists he was working through "official channel" for Ukraine policy

3:45 p.m.: Volker strongly defended himself in his prepared opening statement, denying that he, U.S. Ambassador to the EU Gordon Sondland and Energy Secretary Rick Perry formed a separate "irregular" channel informing Ukraine policy, an effort for which they were known as the "three amigos." Volker, who has a long career in foreign service, also denied he had any knowledge of Mr. Trump asking Ukraine to investigate the Bidens.

"At no time was I aware of or knowingly took part in an effort to urge Ukraine to investigate former Vice President Biden," Volker said. He added that his role was "not some irregular channel, but the official channel."

Volker expressed concern that the ongoing discussion about Ukraine had impacted American efforts in Ukraine, saying "it is a tragedy for the United States and for Ukraine that our efforts in this area, which were bearing fruit, have now been thrown into disarray."

Volker said he connected Zelensky's adviser, Andriy Yermak, with Rudy Giuliani in an attempt to convince Giuliani that the Ukrainian government was not against Mr. Trump. He said he never considered Giuliani "to be speaking on the president's behalf."

Volker consulted with Yermak in August about a statement Zelensky would give to say that Ukraine was opening investigations. The statement did not mention Burisma or the Bidens. Volker said he was unaware at the time of any connection between the hold on security and the release of a statement.

Finally, Volker said, he never used the term "three amigos," and added, "I frankly cringe when I hear it." He also said he was unaware of any call between Sondland and Mr. Trump on July 26. -- Grace Segers

​Volker says he didn't know of link between military aid and investigations

4:04 p.m.: Volker said he was not aware of any connection in a delay in U.S. military aid to Ukraine and the country announcing investigations.

I opposed the hold on U.S. security assistance as soon as I learned about it on July 18, and thought we could turn it around before it the Ukrainians ever knew or became alarmed about it," Volker said. He added that he viewed the delay "as a U.S. policy problem that we needed to fix internally."

Volker said he first discussed the delay with the Ukrainians at the end of August, after Politico reported the aid was on hold.

"Instead of telling them that they needed to do something to get the hold released, I told them the opposite - that they should not be alarmed, it was an internal U.S. problem, and we were working to get it fixed," he said. "I did not know others were conveying a different message to them around that same time." -- Stefan Becket

​Volker says he viewed Joe Biden's involvement in Ukraine and Hunter Biden's work as "separate" issues

4:10 p.m.: Schiff asked Volker about former Ukrainian prosecutor Yuriy Lutsenko. Volker said he had concerns about the former prosecutor's credibility, who had wrongly smeared former U.S. Ambassador Marie Yovanovitch. Volker said he and others have strong confidence in Yovanovitch's integrity.

Volker also expressed his confidence in the integrity of former Vice President Joe Biden, calling him an "honorable man." He said he viewed Hunter Biden's involvement on the board of Burisma as a separate issue.

"I believe that they were separate," Volker testified. -- Kathryn Watson

​Volker says he would have objected to investigation into Joe Biden

4:16 p.m.: Volker said he would have "objected" to Ukraine opening an investigation into former Vice President Joe Biden. He said he did not realize Mr. Trump saw the request to investigate Burisma as the same as investigating Biden until the July 25 call.

"I think the allegations against Vice President Biden are self-serving and not-credible," Volker said. Volker reiterated that he saw the investigations into Burisma and into Biden as separate, but that in retrospect, he understood how Ukrainian officials could be confused. -- Grace Segers

​Volker now says investigations came up at July 10 meeting

4:19 p.m.: In his closed-door testimony, Volker said "investigations" weren't discussed at a contentious July 10 meeting between U.S. and Ukrainian officials, replying "no" to a question about whether they came up.

But his opening statement Tuesday, Volker revised that account, and said they had been raised, corroborating the accounts of other participants.

"As I remember, the meeting was essentially over when Ambassador Sondland made a generic comment about investigations," Volker said in his statement, referring to Gordon Sondland, the U.S. ambassador to the EU. "I think all of us thought it was inappropriate. The conversation did not continue and the meeting concluded." -- Stefan Becket

​Morrison says call summary was moved to secure server by mistake

4:30 p.m.: Morrison said he reported his concerns about the July 25 call to the NSC legal counsel immediately, and said access to the call record should be restricted.

Morrison said he was not concerned about the content of the call, but worried there would be "political consequences" if more people had access to the call summary. Morrison said NSC legal counsel John Eisenberg subsequently told him the call had been placed in a highly secure server, which Eisenberg said was the result of an "administrative error" and a "mistake."

"Had you ever asked the NSC legal adviser to restrict access before?" Democratic counsel Daniel Goldman asked.

"No," Morrison said. -- Grace Segers

​Volker said Zelensky believed Trump misunderstood him

4:34 p.m.: Volker testified that a White House meeting with Zelensky and Mr. Trump was so critical because Zelensky felt Mr. Trump misunderstood him. Mr. Trump, Volker noted, seemed to have a negative impression of the people working around Zelensky.

But Zelensky, Volker testified, was keen on rooting out corruption, and wanted to make sure Mr. Trump saw that.

Zelensky was also popular, having won 73% of the vote. Still, Zelensky knew his standing in Ukraine would be bolstered by images of a meeting between him and Mr. Trump. -- Kathryn Watson

​Volker says investigations would have been "helpful" for securing meeting

4:44 p.m.: Volker testified he did not believe a statement announcing the launch investigations was a condition for setting up a White House meeting, but said he thought it would be "helpful" in getting a meeting scheduled.

"If we didn't have a statement, I wasn't giving up, and thinking, 'Oh, we'll never have a meeting,'" Volker said.

A statement was ultimately never made, and Zelensky has yet to visit the White House. -- Grace Segers

​Nunes calls Democrats' strategy a "drug deal"

4:59 p.m.: Nunes started out the majority's 45-minute questioning by saying he had "bad news" for the witnesses -- TV ratings are "way down" for the hearing. That, he said, shouldn't be taken personally.

"Whatever drug deal Democrats are cooking up, Americans aren't buying," Nunes said before handing over the questioning to the counsel for the Republicans.

"Drug deal" is the same term former national security adviser John Bolton used to describe the push to get Ukraine to investigate the Bidens. -- Kathryn Watson

​Volker said he didn't see anything unusual about hold on aid

5:02 p.m.: Volker testified he did not find it unusual that the administration had placed a hold on providing assistance to Ukraine.

"I just assumed it was part of the decision-making process," Volker said, adding that he had seen holds on aid in previous administrations. He also said he thought the hold had to do with a fear that Zelensky would not be a reformer.

He also testified that Mr. Trump had a "strongly negative view" of Ukraine, but said the president's skepticism was reasonable given Ukraine's history of corruption. -- Grace Segers

​Volker: "I was never involved in anything that I consider to be bribery at all"

5:27 p.m.: Steve Castor, the Republican counsel, questioned Volker about whether he was involved in a quid pro quo or in bribery. Recently, some Democrats, including Speaker Nancy Pelosi, have taken to referring to Mr. Trump's call for an investigation into the Bidens as "bribery."

"I was never involved in anything that I consider to be bribery at all," Volker said. "Or extortion," he added at Castor's prompting. -- Grace Segers

​Morrison says he didn't hear anything that concerned him in July 25 call

5:33 p.m.: Morrison, asked by the Republican counsel whether he heard anything that concerned him during Mr. Trump's July 25 phone call with Zelensky, said, "no."

That comment is sure to be repeated by Republicans as evidence that the president's request of Zelensky wasn't wrong. He also said he viewed the summary of the call later released by the White House as complete and accurate.

But Morrison did also express concern that legal representatives from the National Security Council weren't present on the call, and feared the call would leak. -- Kathryn Watson

​Morrison discusses concerns about Vindman's judgment

5:35 p.m.: Republican counsel Steve Castor asked Morrison about concerns within the NSC about Alexander Vindman's judgment. He asked Morrison about concerns his predecessor, Fiona Hill, might have had, but Morrison's lawyer said the question was outside the scope of his testimony.

Morrison did reference his earlier testimony, in which he said others had raised concerns about Vindman potentially leaking information, something Vindman denied earlier in the day.

Morrison also said he was surprised that Vindman did not come to him about concerns regarding the July 25 call, but instead went straight to the NSC legal counsel.

"If he had concerns about the content of the call, that's something I would've expected to be notified about," Morrison, Vindman's superior, said. In his testimony Tuesday morning, Vindman said that he was told by former National Security Adviser John Bolton -- Morrison's supervisor -- to go straight to the NSC legal counsel with his concerns.

Morrison also testified that Vindman became frustrated over then being excluded from some important meetings relating to Ukraine policy. -- Grace Segers

Schiff adds 30 more minutes of staff questions

6:03 p.m.: After a recess, Schiff tacked on two more 15-minute sessions controlled by him and Nunes, before moving on to member questions. -- Rebecca Kaplan

​Morrison discusses "the Gordon problem"

6:16 p.m.: Morrison testified that he didn't always follow through on suggestions from Sondland. He said his predecessor, Fiona Hill, had dubbed Sondland's role in forming Ukraine policy as "the Gordon problem."

"I didn't necessarily always act on things Gordon suggested," Morrison said. Several witnesses have now testified that Sondland had an outsized role in the formation of Ukraine policy.

Sondland is testifying before the committee on Wednesday. -- Grace Segers

​Volker says Sondland bringing up investigations at July 10 meeting was an "eyeroll moment"

6:28 p.m.: Volker talked about his participation in a July 10 meeting with Ukrainian officials, which he initially did not recall in his previous testimony. Volker said Sondland brought up "investigations" with the Ukrainian officials, which then led to former National Security Adviser John Bolton cutting the meeting short.

"I thought it was something of an eye roll moment," Volker said. "It was not the time or the place to bring up that." -- Grace Segers

GOP congressman questions credibility of intelligence community

7:12 p.m.: Republican Congressman Brad Wenstrup criticized the intelligence community and questioned the widely accepted conclusion by American intelligence that Russia, and not Ukraine, interfered in the 2016 election.

Wenstrup said that members of the intelligence community were some of the same people who were involved in the "Russia collusion hoax" in the origin of the special counsel investigation.

Wenstrup also compared Giuliani's role in shaping Ukraine policy to that of former basketball player Dennis Rodman in North Korea. However, Rodman did not have a close personal relationship with the president, as Giuliani does. -- Grace Segers

Volker acknowledges he did not fix the "Giuliani problem"

7:26 p.m.: Volker testified that he tried to work with Giuliani in order to convince him, and therefore the president, that the new Ukrainian president was not corrupt. However, he said the July 25 call made him realize Giuliani and the president still believed Ukraine needed to investigate Burisma and the Bidens.

"So it's fair to say you have not fixed the 'Giuliani problem'?" Schiff asked.

"That's correct," Volker said. -- Grace Segers

​Trump weighs in on hearings, calling it a "great day for Republicans"

8:11 p.m.: As the final lawmakers questioned Volker and Morrison in the impeachment hearings, Mr. Trump weighed in on the proceedings, saying it was a "great day for Republicans."

Earlier on Tuesday, Mr. Trump said he had watched a portion of the first hearing, and that Republicans were "killing it." -- Grace Segers