The Republican reaction to President Trump's firing of FBI Director James Comey is instructive: It gives us a preview of how many in the president's party will stand by him if the facts uncovered by the Russia probe take a turn for the worse.

So far, those facts have been relatively few. There have been conspiracy theories, vague allegations backed by appeals to classified information that cannot be shared, undeniable clouds of smoke without a proven fire.

If there is evidence of high-level collusion between the Trump campaign and the Russians, however, the general public hasn't seen it.

The timing of Comey's termination nevertheless has people wondering: What if?

Senate Majority Leader Mitch McConnell, R-Ky., gave a full-throated defense of the president's decision to fire an FBI director many Democrats hold more responsible for the 2016 election outcome than the Russians or WikiLeaks.

"Our Democratic colleagues complaining about the removal of an FBI Director, whom they themselves repeatedly and sharply criticized," McConnell said on the Senate floor. "That removal being done by a man, Rod Rosenstein, who they repeatedly and effusively praised. When Mr. Rosenstein recommended Mr. Comey's removal for many of the very reasons they consistently complained about."

The junior senator from Kentucky, Republican Rand Paul, lamented Washington's "crocodile tears." He noted he had never been a Comey fan and that the fallen FBI chief had plenty of detractors on Capitol Hill.

Not all Republicans have been as sanguine about Comey's removal. Sen. Richard Burr, R-N.C., who chairs a committee doing its own Russia investigation, was "troubled." Sen. John McCain, R-Ariz., was "disappointed." Sen. Ben Sasse, R-Neb., described the timing as "very troubling."

Many Republicans expressed disapproval of how Comey's ouster was handled. House Oversight Committee Chairman Jason Chaffetz, R-Utah, wants the Justice Department's inspector general to look into it.

Whether a political figure survives a scandal often has little to do with the fulminations of the opposition and everything to do with what their own party decides to do. In 1974, a trio of influential Republicans — 1964 presidential nominee Sen. Barry Goldwater, Senate Minority Leader Hugh Scott and House Minority Leader John Rhodes — went to the White House to tell President Richard Nixon he did not have the support in Congress to survive impeachment.

But after the Republican-controlled House approved articles of impeachment against President Bill Clinton with the votes of just five Democrats, it was always obvious that GOP senators weren't going to be able to get the 12 Democrats they needed to vote to convict him in the Senate. In fact, it was just as likely they were going to lose some centrist Republican votes.

Nixon left. Clinton stayed. Their own parties played a major role in achieving those different outcomes.

We're not anywhere near this point yet with Trump or Russia, Democratic invocations of the "i-word" notwithstanding. But it has to trouble the president he has so many fair-weather friends within his own party.

As far back as the campaign, leading Republicans have rallied around Trump when things go well and headed for the tall grass when trouble occurred.

Russia has always been fertile ground for Republican defections because many GOP politicos disagree with Trump's campaign comments about Russian President Vladimir Putin and policy toward Moscow. The Russia question looms as large for the Never Trump Right as the Resistance Left.

If the facts got bad enough, there is little question key Russia hawks like McCain and Sen. Lindsey Graham, R-S.C., would align against the administration. Already there has been an uptick in Republicans calling for either a special prosecutor or an independent committee to investigate Russian interference in the U.S. presidential campaign.

These post-Comey demands have come without any change in the underlying publicly known facts about Russia and the campaign.

Some Democrats have long argued that getting Republicans to abandon Trump and marginalize him within his own party should be a key part of their strategy. Schumer once predicted this would happen in three or four months.

As evidenced by the happy scene between the president and congressional Republicans in the Rose Garden after the American Health Care Act passed the House, that prediction hasn't come true.

The Senate hearings on Russia earlier this week also confirmed that many Republicans agree with the White House that "unmasking" and leaks are the real, or at least comparatively important, issues.

Yet the tepid Republican response to Trump's dismissal of Comey ought to remind him that this reservoir of goodwill among the GOP's governing class only runs so deep.