Late in Monday’s marathon hearing of the House Intelligence Committee, FBI Director James Comey reminded the nation that he was something of a hostile witness, reluctantly summoned to talk about Russia, Donald Trump and the 2016 campaign.

“I’d rather not be talking about this at all,” Comey said. “Now we are going to close our mouths and do our work.”

Before Comey returned to his offstage role, he dropped enough bombshells to solidify his reputation as the most significant FBI director since J. Edgar Hoover. Comey gave an artful lesson in how to stick a shiv into a sitting president without ever raising his voice or making a specific accusation.

Early in the hearing, Comey shredded Trump’s cockamamie Twitter claim that Barack Obama had wiretapped him before the election. As Comey solemnly stated, “I have no information that supports those tweets and we have looked carefully inside the FBI.”

Comey had arrived at the hearing with his own smoking gun that he brandished at the beginning of his opening statement — official confirmation that the FBI is investigating “any links between individuals associated with the Trump campaign and the Russian government and whether there was any coordination between the campaign and Russian efforts.”

Comey’s offensive against the White House even extended to refuting a presidential tweet about the ongoing hearing. Connecticut Democratic Rep. Jim Himes asked Comey to respond to a Trump tweet claiming, “The NSA and FBI tell Congress that Russia did not influence the electoral process.” Comey dismissed Trump’s fanciful version of the truth by saying, “It wasn’t certainly our intention to say that today.”

J. Edgar Hoover battled with many presidents — particularly John F. Kennedy and his brother Robert — but those struggles took place behind closed doors.

In contrast, Comey’s strength rests on his ability to portray himself as the last reasonable man in America animated by nothing more than a passion for justice and truth. That attitude of unshakable rectitude can lead Comey into dangerous places — such as his maladroit announcement before the election that he had reopened an investigation into Hillary Clinton’s e-mails.

But Comey’s record in helping upend Clinton gives him a rare credibility in opposing the Trump White House. Comey may make mistakes as an overzealous crusader, but it is hard to ascribe partisan motives to a man who many Democrats believe put Trump in the Oval Office.

For all the wild theories out there it is impossible to predict how this investigation will play out. Is this a Russian house of cards or is this Watergate revisited with tweets instead of White House tapes?

What seems politically baffling, though, was the zeal of committee Republicans, led by Chairman Devin Nunes, to risk their own credibility to protect the Trump White House.

During the early hours of the hearing, there was bellowing GOP outrage over the leaks that doomed National Security Adviser Michael Flynn. Conveniently missing from the Republican storyline was that Flynn had lied to Vice President Mike Pence, had been a registered foreign agent on behalf of Turkish interests while advising the Trump campaign, and had collected $68,000 from Russian entities in 2015.

Florida Republican Ileana Ros-Lehtinen was the rare committee member who seemed more interested in asking actual questions than in scoring partisan talking points. Ros-Lehtinen, who refused to endorse Trump during the campaign, was rewarded with a significant payoff when she inquired whether Russia’s intervention in 2016 was different from in prior elections.

Comey warned that the Russians are likely to resort to more aggressive election-year meddling in 2018 and 2020 because they feel they successfully “introduced chaos and division” into the presidential race. Rogers echoed this view by saying that Moscow felt that it was “a positive outcome for them in ... calling into question the democratic process.”

The details of any FBI investigation into the ties between the Trump campaign and Putin’s henchmen are likely to remain shadowy unless and until there are indictments. That is appropriate in a legal sense, but it does little to resolve the larger question of whether our democracy was compromised in 2016.

A major reason why the Senate Watergate Committee is remembered as a shimmering moment is because there was a bipartisan commitment to ferreting out the facts about Nixon’s complicity.

Whether a similar special committee or outside commission can be created on Russia depends on one thing — the willingness of Republicans to pursue the facts rather than slavishly defend a president with a shaky allegiance to democracy and a shakier grasp of truth.

Roll Call columnist Walter Shapiro is a veteran of Politics Daily, USA Today, Time, Newsweek and The Washington Post.