House Speaker Paul D. Ryan (R-Wis.) meets with reporters following a closed-door Republican strategy session on Capitol Hill in Washington on Tuesday. (J. Scott Applewhite/AP)

Top Republican leaders on Capitol Hill expressed confidence Tuesday that special counsel Robert S. Mueller III will be able to finish his Russia investigation unimpeded, despite President Trump’s recent attacks on the probe. 

The remarks from House Speaker Paul D. Ryan (R-Wis.) and Senate Majority Leader Mitch McConnell (R-Ky.) come after Trump leveled the most direct criticism to date of Mueller and the credibility of his investigation — a dramatic move by the president that has nonetheless done little to make GOP lawmakers fret publicly that the special counsel could soon be dismissed.

In a news conference Tuesday, Ryan said he has been assured Mueller’s firing is not being discussed but declined to elaborate on who provided that assurance.

“Look, first of all, the special counsel should be free to follow through his investigation to its completion without interference, absolutely. I am confident he will be able to do that,” Ryan said. “I have received assurances that his firing is not even under consideration. We have a system based upon rule of law in this country. We have a justice system, and no one is above that justice system.”

McConnell was equally confident when he addressed reporters Tuesday afternoon. 

“I think it was an excellent appointment,” McConnell said of Mueller. “I think he will go wherever the facts lead him, and I think he will have great credibility with the American people when he reaches the conclusion of this investigation.”

That display of public confidence from the highest tiers of GOP leadership — reflected down to the rank-and-file — showed how Trump’s latest and most aggressive attack on the special counsel’s investigation into Russia’s interference in the 2016 elections was likely to pass with little substantive pushback from Capitol Hill.

Republicans continue to say that despite his rhetoric, they do not believe Trump would take steps to dismiss Mueller because doing so would be catastrophic. One member who has spoken directly to Trump in recent days — House Freedom Caucus Chairman Mark Meadows (R-N.C.) — says the president is venting frustration but has no plans to take steps toward ousting Mueller.

White House officials continue to say there is no plan to fire Mueller, even though Trump believes the investigation is a waste of time.

“Look, the president has been very clear about the fact that there was no collusion between his campaign and any other entity,” White House press secretary Sarah Huckabee Sanders said Tuesday. “However, to pretend like going through this absurd process for over a year would not bring frustration seems a little bit ridiculous.”

There have been exceptions among congressional Republicans, who have generally tried to ignore or minimize Trump’s attacks on the investigation. Sen. Jeff Flake (R-Ariz.) said Tuesday he has relayed a plea to White House officials, whom he declined to identify: Dissuade the president from taking action against Mueller. 

“I don’t know that that matters,” Flake said Tuesday. “He’s going to do what he’s going to do. Obviously, those on staff aren’t encouraging him to fire Mueller. This will be his thing, but he seems to be closer to it than ever.”

Flake, one of Trump’s most prominent critics, said he would support impeachment proceedings against Trump if the president ends the investigation “without cause.”

“We’re begging him, ‘Don’t go down this road. Don’t create a constitutional crisis. Don’t force the Congress to take the only remedy that Congress can take,’ ” Flake said. “To remind the president of that is the best way to keep him from going down that road. To fire Mueller without cause, I don’t know if there is any other remedy left to the legislative branch.”

Sen. Lindsey O. Graham (R-S.C.) also warned Tuesday that ousting Mueller would “probably” be an impeachable offense.

“I think what the president will have done is stopped an investigation in whether or not his campaign colluded with the Russians, what effect the Russians had on the 2016 campaign,” Graham said on conservative host Hugh Hewitt’s radio show Tuesday morning. “I can’t see it being anything other than a corrupt purpose.”

But Flake and Graham have been outliers, and Democrats said that most Republicans are willfully blind to the possibility of Mueller’s firing, arguing Trump has proved during his presidency that he will make rash decisions opposed by his aides and party leaders.

“People who have thought well of Donald Trump have usually been mistaken,” Rep. Jerrold Nadler (D-N.Y.), the top Democrat on the House Judiciary Committee.

Sen. Christopher A. Coons (D-Del.), who has written legislation to protect the special counsel in case of a firing, has been trying to persuade Republicans in dozens of recent conversations to sign on to his bill, with little traction. He argued that GOP senators don’t want to contemplate what they would be forced to do should a firing occur. 

“If we do not have a coherent plan for how to address an abrupt firing of Bob Mueller, then we are failing to do our job,” Coons said. Referring to the recent dismissal of Secretary of State Rex Tillerson, the Delaware senator added: “If you think President Trump is going to hesitate to do something dramatic and bold like firing Rod J. Rosenstein or Jeff Sessions, you’re just not watching the show.” 

Rosenstein, the deputy attorney general, took over supervision of the Mueller probe last year because of Attorney General Jeff Sessions’s recusal from the Russia inquiry. Trump cannot directly dismiss Mueller and would have to direct Rosenstein to fire him — a scenario GOP lawmakers say won’t happen. But Trump could also fire Rosenstein and replace him with someone who would end the probe. 

Coons’s legislation, authored with Sen. Thom Tillis (R-N.C.), as well as a similar measure from Sens. Graham and Cory Booker (D-N.J.) intended to protect the special counsel, have languished in Congress for months. Trump’s latest verbal assault has done little to persuade Republicans that legislation is needed. Democratic leaders negotiating a must-pass government spending bill tried to insert language into the bill to protect the special counsel, but were rebuffed by Republicans, according to one person familiar with the back-and-forth who spoke on the condition of anonymity to discuss private talks.

“I just don’t think it’s necessary,” McConnell said of action to shield the special counsel. “I don’t think Bob Mueller is going anywhere. I think there’s widespread feeling, and the president’s lawyers obviously agree, that he ought to be allowed to finish the job.”

 Mike DeBonis, Robert Costa and Ed O’Keefe contributed to this report.