Republican senators scrambling to protect President TrumpDonald John TrumpKamala Harris calls for Twitter to suspend Trump account over whistleblower attacks Clinton jokes she 'never' had to tell Obama not to 'extort foreign countries' John Dean: 'There is enough evidence' to impeach Trump MORE from a formal impeachment inquiry are attacking the credibility of the whistleblower who filed a complaint.

GOP lawmakers are asserting the whistleblower did not have firsthand knowledge of the actions detailed in the complaint and question whether the person had a political agenda.

“It doesn’t come from a person with personal knowledge. It’s like I heard these people say this, and now I’m reporting it. I think that is pretty bizarre,” said Sen. John CornynJohn CornynThe Hill's 12:30 Report: Trump steps up attacks on whistleblower, Schiff GOP senators attack whistleblower's credibility Republicans show signs of discomfort in defense of Trump   MORE (R-Texas).

“Secondly, after a certain point, it doesn’t just allege facts, it really is kind of a dossier or political diatribe, so I think there are plenty of reasons to be skeptical. Having said that, we are in the process of talking to the director of national intelligence and the inspector general.”

Sen. Chuck GrassleyCharles (Chuck) Ernest GrassleyIntel community watchdog appears to push back on Trump allegations of changes to whistleblower rules GOP senators urge Barr to probe Clinton, Ukraine GOP senator: Trump has changed presidency 'not necessarily toward the positive' MORE (R-Iowa), who has had a reputation for protecting whistleblowers, said the one at the center of the Trump impeachment inquiry didn’t necessarily deserve protections.

“If they are not really a whistleblower, they don’t get the protection,” he said.

The remarks from Grassley, Cornyn and other senators echo arguments coming from Trump, but stand in stark contrast to the testimony last week from acting Director of National Intelligence Joseph MaguireJoseph MaguireOvernight Defense: Dems subpoena Giuliani for Ukraine docs | DOJ says Trump contacted foreign countries over Russia inquiry | Top Armed Services Republican Thornberry to retire | Milley sworn in as top general Trump: White House 'trying to find out' whistleblower's identity Trump suggests Schiff be arrested for treason for exaggerating call with Ukraine MORE, who said the whistleblower acted in good faith.

“I think the whistleblower did the right thing,” Maguire told the House Intelligence Committee.

But Senate Judiciary Committee Chairman Lindsey GrahamLindsey Olin GrahamIntel community watchdog appears to push back on Trump allegations of changes to whistleblower rules Democrats demand Barr, senior officials testify on Ukraine The Hill's 12:30 Report: Trump steps up attacks on whistleblower, Schiff MORE (R-S.C.) said reading the whistleblower’s complaint “makes me more suspicious about how all this happened.”

“I want to know who was the person that went to the whistleblower,” he said.

Graham said that whistleblowers typically report witnessing basic facts and firsthand evidence and raised concern about what some Republicans see as a not-so-subtle attempt to draw up a criminal indictment of Trump.

“This was a fairly sophisticated effort to write a narrative rather than blow a whistle,” he said.

A Senate Republican aide predicted that the whistleblower’s name will likely become public either because that person will agree to testify publicly or the name will leak to the press.

The attacks on the whistleblower come with high stakes, as GOP leaders see their political fate as closely tied to Trump’s in next year’s elections.

Several Republican lawmakers publicly and privately acknowledged over the past week that the content of the transcript of a July 25 call between Trump and Ukrainian President Volodymyr Zelensky, in which Trump urged Ukrainian officials to investigate Democratic presidential candidate Joe BidenJoe BidenKamala Harris calls for Twitter to suspend Trump account over whistleblower attacks Clinton jokes she 'never' had to tell Obama not to 'extort foreign countries' John Dean: 'There is enough evidence' to impeach Trump MORE, was damaging.

Sen. Mitt RomneyWillard (Mitt) Mitt RomneyTo win the federal paid family leave debate, allow states to lead the way Democrat argues GOP had 'no deep love or loyalty' to Trump Flake tells GOP: Trump 'does not deserve reelection' MORE (R-Utah) called the transcript “troubling in the extreme” while Sen. Ben SasseBenjamin (Ben) Eric SasseDemocrat argues GOP had 'no deep love or loyalty' to Trump Juan Williams: Trump's grip on GOP Senate may come loose GOP senators attack whistleblower's credibility MORE (R-Neb.), who recently secured Trump’s endorsement for reelection, warned “there’s obviously lots that’s very troubling here.”

A handful of Republicans have expressed shock that Trump released the transcript of the president’s conversation with Zelensky and an unredacted version of the whistleblower complaint, fearing it gave Democrats ammunition.

A GOP senator who requested anonymity to discuss party strategy said that White House officials and GOP leaders decided the damaging information was likely to become public anyway and thought the best strategy was to get it out early so Republicans could then have a chance to wage a counteroffensive.

“This was all going to become public. The thought was the sooner it does, the better. Get it all out quickly,” the lawmaker said.

And other Republicans offered other surprise defenses of Trump.

Sen. John KennedyJohn Neely KennedyMORE (R-La.) compared Trump’s conduct to a police officer who beats up a suspect while arresting them.

“This is the way I analyze this ... I look at this like a guy robs a bank and on the way to jail the cops beat the bejesus out of him.” Kennedy said. “Should cops beat the bejesus out of suspects? No. Should it be investigated? Yes. But you can’t ignore the alleged bank robbery either."

As part of that counteroffensive strategy, Republican lawmakers have sought to shift the public focus off of Trump and onto Biden.

House Minority Leader Kevin McCarthyKevin Owen McCarthyOcasio-Cortez blasts McCarthy as a 'bumbling, sloppy, dishonest mess' over Trump defense The Hill's Morning Report - Dems to hit gas on impeachment GOP senators attack whistleblower's credibility MORE (R-Calif.) told reporters Thursday that it was perfectly acceptable for Trump to ask Zelensky to participate in a Department of Justice investigation of what role Biden and his son Hunter Biden, a paid board member to a Ukrainian gas company, might have had in quashing a Ukrainian corruption investigation.

Sen. Ron JohnsonRonald (Ron) Harold JohnsonIntel community watchdog appears to push back on Trump allegations of changes to whistleblower rules GOP senators urge Barr to probe Clinton, Ukraine GOP senator: Trump has changed presidency 'not necessarily toward the positive' MORE (R-Wis.) said Trump has a responsibility “as the head law enforcement official of the nation” to delve into efforts by U.S. officials to interfere in foreign corruption investigations and to probe efforts from abroad to interfere in U.S. elections.

One of the controversial subjects Trump alluded to in his conversation with Zelensky was an allegation that a Russia-orchestrated hacking of the Democratic National Committee in 2016 was conducted in Ukraine. There has been little evidence to substantiate that claim.

Johnson sees Trump’s interest in Biden’s Ukraine connections and Ukraine’s alleged role in meddling in the 2016 election as legitimate law enforcement interests.

GOP leaders have sought to tamp down criticism of Trump from their ranks, mindful that that unity among rank-and-file members is crucial to maintaining their political strength, a point that Senate Majority Leader Mitch McConnellAddison (Mitch) Mitchell McConnellOvernight Defense: Dems subpoena Giuliani for Ukraine docs | DOJ says Trump contacted foreign countries over Russia inquiry | Top Armed Services Republican Thornberry to retire | Milley sworn in as top general The Hill's 12:30 Report: Trump steps up attacks on whistleblower, Schiff US sanctions Russian individuals for interference in 2018 elections MORE (R-Ky.) frequently makes to colleagues.

Graham, one of Trump’s staunchest allies, told reporters on Wednesday that Romney was the only senator to voice concerns about Trump’s conduct at a private lunch meeting of the Senate Republican Steering Committee.

And Sen. James InhofeJames (Jim) Mountain InhofeGOP senators attack whistleblower's credibility Overnight Defense — Presented by Huntington Ingalls Industries — Intel chief defends handling of whistleblower complaint | Complaint alleged attempt to cover-up Ukraine call | US to send 200 troops to Saudi Arabia | Senate confirms Joint Chiefs No. 2 Senate confirms general accused of sexual assault MORE (R-Okla.), another Trump ally, sought to portray Romney as a disgruntled outlier. “Mitt Romney doesn’t like the president and he’s going to say a lot of things I don’t agree with,” he said.

The White House in recent days has worked closely to coordinate its defense with allies on Capitol Hill.

A White House aide accidentally sent a copy of its talking point for Republican lawmakers to Democratic offices on Wednesday.

The document argued that Trump made no quid-pro-quo request to Zelensky and discussed Biden only after Zelensky initiated the conversation about corruption-related issues.

The talking points also shifted scrutiny to the whistleblower by arguing the “real scandal” was that Trump’s confidential conversation with a foreign leader was leaked to the press.

The document reflected Johnson’s argument that it was proper for Trump to ask a foreign leader to investigate any connection between his country and attempted interference in the 2016 election.

Republicans strategists acknowledge their prospects in the 2020 election, when control of the Senate as well as the White House and House will be up for grabs, are closely tied to Trump’s.

A Republican strategist working on a congressional campaign in Iowa said that, for example, while Sen. Joni ErnstJoni Kay ErnstOvernight Health Care: Dem seeks changes to Pelosi drug pricing bill | Trump officials shift family planning funds from Planned Parenthood | CVS halts sales of Zantac over cancer concerns To win the federal paid family leave debate, allow states to lead the way GOP senators attack whistleblower's credibility MORE (R-Iowa), who is up for reelection, has a strong independent brand and could outperform Trump by a few points, she would likely lose if Trump lost her state by 5 points or more.

Ernst has said the investigation of the whistleblower’s complaint should be handled on a bipartisan basis by the Senate Intelligence Committee.

Another GOP tactic has been to portray the Democrats as dead-set on impeachment regardless of what any investigation of the whistleblower’s complaint turns up.

This line of argument has been spearheaded by McConnell.

“We know that House Democrats have been indulging in their impeachment obsession for nearly three years now, a never-ending impeachment parade in search of a rationale,” he said on the Senate floor the morning after Speaker Nancy PelosiNancy PelosiJohn Dean: 'There is enough evidence' to impeach Trump Ocasio-Cortez blasts McCarthy as a 'bumbling, sloppy, dishonest mess' over Trump defense DOJ says Trump contacted foreign countries to assist Barr's Russia inquiry MORE (D-Calif.) announced the launch of a formal impeachment inquiry.

McConnell pointed out that on the day of Trump’s inauguration, The Washington Post ran a headline stating, “The campaign to impeach President Trump has begun.”