Republicans in the Senate are going to be under a political microscope as they consider President Trump's forthcoming nominee to replace James Comey as FBI Director.

There could be major implications for the 2018 elections. Republicans hold the Senate majority, and therefore the fate of Trump's pick to lead the FBI after Comey in their hands, and they will have to answer for their confirmation vote in the midterm.

"The politics to watch is key GOP senators' positions on Comey's replacement," said a Republican strategist who advises incumbent senators and requested anonymity in order to speak candidly. "The White House will need them to be on board. They will take this very seriously."

The president's firing of Comey on Tuesday comes in the midst of an ongoing investigation into Russian meddling in the 2016 elections that could implicate his own campaign.

Trump's Democratic critics, and even his GOP skeptics, were dismissive of the administration's stated reasons for removing Comey.

They charged that Trump acted because he wants to install a "stooge" who will shield him scrutiny, as opposed to losing confidence in Comey's leadership because he acted improperly and treated Hillary Clinton unfairly during the FBI probe of her use of a private email server while she was secretary of state.

This deep suspicion could ratchet up the pressure on Republicans as they consider their confirmation vote for Trump's choice to succeed Comey.

That was evident as statements, ranging from cautious to scolding, poured in from Republican senators reacting to Comey's removal. Senate Intelligence Chairman Richard Burr, R-N.C., leading a bipartisan investigation into Russian influence in the 2016 campaign and was re-elected just last year, wasn't happy.

"I am troubled by the timing and reasoning of Director Comey's termination," Burr said.

"I have found Director Comey to be a public servant of the highest order, and his dismissal further confuses an already difficult investigation by the Committee," he continued. "In my interactions with the Director and with the Bureau under his leadership, he and the FBI have always been straightforward with our Committee. Director Comey has been more forthcoming with information than any FBI Director I can recall in my tenure on the congressional intelligence committees. His dismissal, I believe, is a loss for the Bureau and the nation."

Senate Republicans begin the 2018 election cycle on offense, with far more seats on their target list than Democrats have on theirs. But Senate Majority Leader Mitch McConnell, R-Ky., with the 2010 GOP wave still fresh in his mind, has warned his party not to rely on the map for success.

Democrats began that cycle in a similarly advantageous position; they ended up losing seven seats.

Consideration and confirmation of a new FBI director puts yet another political challenge on their plate, right as they are trying to write a health care reform bill and plan for a tax overhaul and a politically sensitive debt ceiling hike. Republican operatives worry that it could be too much to handle, disrupting plans to bring home deliverables to their voters in time for the midterm.

"It's a nightmare for the agenda," a Republican lobbyist said. "Trump just asked McConnell to pull another rabbit out of his hat and we are running out of rabbits."

Some Republican insiders Comey's firing could nevertheless end up being a problem for Democrats.

The issue might further fixate them on Trump and Russia, distracting them from focusing on kitchen table issues like jobs and the economy that usually drive votes. It might also make them look silly, arguing that Comey shouldn't have been fired for the very malfeasance they have insisted for months that he was guilty of — mishandling the investigation into Clinton's email server.

The Justice Department, in a memo to Trump recommending Comey's removal, cited his July press conference detailing Clinton's "careless" use of a private email server, and his letter to Congress in late October informing that the FBI was re-examining the matter. The argument echoes complaints from Democrats, who are now apoplectic over Trump's firing, because, they charge, he wants to shut down the inquiry into his presidential campaign's possible ties to Russia.

"This pushes Democrats even further from the center of the electorate. Only a complete partisan could call for someone's ouster for six months only to be outraged when he gets axed," a Republican operative said.

Still, that was the minority view in exchanges the Washington Examiner had late Tuesday with nearly a dozen GOP insiders, strategists and lobbyists, including those who live far outside the Beltway.

The worry was that Americans wouldn't buy Trump's reasoning — that the Clinton investigation was mishandled — and that the move would be seen as a power grab to stifle an unfriendly inquiry that Republicans in Congress would have difficulty defending.

"I can't figure it out," said a Republican consultant who is based out west. "This only makes the Russia investigation politics worse. Russia now clear needs an independent investigator."