The fate of Donald Trump’s presidency hinges on an impeachment case that is unfolding faster than Congress can keep up.

An explosive interview by an associate of Rudy Giuliani and a government watchdog’s report that Trump’s freeze of Ukraine military aid violated the law immediately shook up the political and strategic calculus for lawmakers just hours before the start of Trump’s impeachment trial. The associate, Lev Parnas, could even be called as a witness in the Senate trial.

“Evidence is coming in every day that supports our case,” said Rep. Val Demings (D-Fla.), one of seven impeachment managers who will be prosecuting the case against Trump in the Senate trial.

“All of this continues to underscore the need for witnesses and documents,” added Rep. Jason Crow (D-Colo.), another impeachment manager.

Democrats remain hopeful that the revelations will dial up pressure on Senate Republicans weighing whether to seek witnesses and documents in the trial. It has already provided the House’s impeachment managers new angles to lay out their case against Trump, as they race to prepare for opening arguments expected to begin Tuesday.

So far, Senate Republicans appear unmoved.

“They were in such a hurry that they didn’t get all this information? What the heck, OK?” said Sen. Joni Ernst (R-Iowa), blaming House Democrats for impeaching Trump before waiting to develop additional strains of evidence. “So let’s focus on the record. They obviously felt they had enough information to impeach the president with what they had. Let’s take a look at what they had.”

Still, the new developments underscore the peril facing GOP senators as the trial begins and whether to heed Democrats’ urgent demands to call witnesses like former national security adviser John Bolton and senior White House officials who have firsthand knowledge of Trump’s actions in the Ukraine saga.

“They’re afraid of the truth,” Speaker Nancy Pelosi said. “This is just another avoiding of the facts and the truth on their part. They don’t want to see documents, they don’t want to hear from eye witnesses, they want to ignore anything new that comes up.”

The House impeached Trump last month over allegations that he pressured Ukraine to investigate his Democratic rivals, including former Vice President Joe Biden. Democrats say the evidence is clear that Trump withheld military aid from the beleaguered ally, which is engaged in an active war against Russian invaders, in order to boost his political standing. Then, the impeachment articles charge, Trump stonewalled investigations of the matter to prevent it from becoming public.

House Democrats received startling new ammunition this week from Parnas, an indicted associate of Giuliani, who also turned over to lawmakers hundreds of pages of text messages, emails, photos and other information that corroborated his case. In an interview Wednesday night on MSNBC, Parnas implicated several additional senior officials in the alleged scheme, including Vice President Mike Pence and Attorney General William Barr, who all rejected the claims.

“This is an example of all of the president’s henchmen, and I hope that the senators do not become part of the president’s henchmen,” Pelosi said.

But Democrats — in particular, those who will be presenting the case to the Senate — were relatively subdued as they reacted to the revelations on Thursday, noting that Parnas, who faces serious legal jeopardy for alleged campaign-finance crimes, should not be presumed to be trustworthy.

“I don’t know how it changes the case because we certainly start with someone who has had his issues,” Demings said of Parnas, adding that he “started on the wrong side” and might be “trying to right [his] wrongs.”

“We’re listening — and not making any judgments,” Demings said. “I haven’t put him in any category yet.”

House Intelligence Committee Chairman Adam Schiff (D-Calif.), the lead impeachment manager, was similarly noncommittal, saying in a statement that his panel was “continuing to review his interviews and the materials he has provided to evaluate his potential testimony in the Senate trial.”

Senate Republicans downplayed both developments, even as the new details seemed to unsettle and intensify the case against Trump.

“I don’t think that changes anything,” Sen. John Cornyn (R-Texas) said of the non-partisan Government Accountability Office report.

Sen. Rand Paul (R-Ky.) went further, arguing that GAO got it wrong when the agency concluded the White House violated the Impoundment Control Act by declining to notify Congress of the delay in appropriated funds.

“I think they misunderstand the law. I think presidents withhold money all the time, move money around,” Paul said. “I think there’s a great deal of latitude to what presidents do. So I think they’ve misinterpreted the law.”

GOP senators also questioned Parnas’ credibility, given the charges against him.

“I wouldn’t trust him as far as I could throw him,” said Sen. Lindsey Graham (R-S.C.).

But Democrats cited both developments to underscore the urgency of holding a trial that includes witnesses and documents, rather than quickly proceeding to a final vote on whether to remove Trump from office.

Sen. Doug Jones of Alabama, a Democrat facing a tough re-election campaign, said the last 24 hours have bolstered his party’s case to hear from witnesses and subpoena documents. He called the GAO report’s conclusion “pretty serious, pretty strong.”

“The president gave an order to take illegal action … so this is obviously a very important part of the evidence that will be before the Senate during the trial,” said Sen. Chris Van Hollen (D-Md.) who released the GAO report. “What Parnas’ statement underscores is the importance of getting relevant witnesses and documents. He had a lot to say.”

“At this point [it] would be a dereliction of constitutional duty not to support fact witnesses,” he added.

Several key Republicans including Mitt Romney of Utah and Lisa Murkowski of Alaska said they had not reviewed the GAO report, and declined to comment on the possibility of bringing in Parnas.

And Trump’s allies scoffed at the new revelations.

Sen. Mike Braun (R-Ind.) said his views on the contours of the trial have “probably not” changed and that he would not want to restrict the executive branch’s “ability … to hold something if you thought it had to be done.”

In other words, GOP unity on McConnell’s plan to punt the decision on witnesses appeared to show no cracks; Romney said the matter will be largely up to the impeachment managers anyway.

Heather Caygle, John Bresnahan, and Marianne LeVine contributed to this report.