WASHINGTON (CNN) -- America faces a fateful choice: Does it believe Donald Trump or James Comey?

A theatrical showdown is now looming between the President with a hazy relationship with the truth and the FBI director he fired, whose finely tuned sense of his own integrity has often steered him into rocky political waters.

The epic head-to-head was set up by stunning allegations that in February Trump pressured Comey to shut down the FBI's Russia probe that was, among other avenues of inquiry, investigating former national security adviser Michael Flynn.

Furthermore, in a sensational development, sources told The New York Times and then CNN on Tuesday night that Comey wrote down his account of Trump's request over the probe in a memo that is about to become one of Washington's most famed artifacts.

The coming confrontation between Comey and Trump is more than just an opportunity to air grievances that appear to have quickly grown between the two men during their short working relationship and over the FBI director's humiliating dismissal -- news of which he learned on cable television just one week ago.

It promises to have grave implications for the longevity of an administration that appears to slip deeper into utter disarray by the hour. There doesn't seem to be a way that both men could survive the contest with their reputations intact.

Compelling evidence

Comey is the kind of adversary that no White House would relish.

If the claims in his memo are correct, they would appear to offer the most compelling evidence yet that Trump's attempt to shut down the probe could amount to an obstruction of justice that imperils his presidency.

"It looks like he was trying to impede the investigation," said CNN senior political analyst David Gergen. "He was using his power to do that, and when James Comey didn't go along with him, when he wasn't his boy, he fired him."

Gergen suggested the situation was so serious following Tuesday's revelations that America could be on the cusp of a new impeachment drama.

The White House has dismissed Comey's version of events revealed by a memo that was described to CNN.

"While the President has repeatedly expressed his view that General Flynn is a decent man who served and protected our country, the President has never asked Mr. Comey or anyone else to end any investigation, including any investigation involving General Flynn," a White House official said in a statement.

The prospect of a new arm's length confrontation with Comey might also be causing Trump to second guess himself after suddenly firing the former director last week, then admitting on television that he did so because he was frustrated about a Russia probe he has called a waste of taxpayer money.

Given the stakes, it now appears certain that Comey will be called out of his premature retirement to testify before Congress about the memo. He would be grilled on what Trump actually said in their Oval Office meeting on February 14 that is now at the center of the political hurricane. Comey would also face scrutiny over why he decided to keep a log of his conversations with the President that was then leaked at a moment of maximum embarrassment for the White House.

'I have my subpoena pen ready'

The Republican Congress hasn't exactly been holding Trump's feet to the fire in the first few months of his administration.

But that may be changing.

Already, Rep. Jason Chaffetz, Republican chairman of the House Oversight Committee, has asked the FBI to provide "all memoranda, notes, summaries, and recordings referring to or relating to any communications between Comey and the president."

"I have my subpoena pen ready," Chaffetz tweeted on Tuesday.

Other lawmakers, grasping the deeply serious twist the Trump crisis took on Tuesday, are also calling for full disclosure.

Sen. Lindsey Graham, R-South Carolina, said that Comey should be called before the Senate Judiciary Committee, on which Graham sits.

"OK, well, he's got to come in and tell us why," Graham said. "We're not going to try somebody on a piece of paper."

So far in the Trump presidency, the most important Republican leaders, House Speaker Paul Ryan and Senate Majority leader Mitch McConnell, have tried to keep the focus of their troops on implementing a conservative agenda rather than holding an unpredictable President to account.

But Ohio Republican Gov. John Kasich said in a CNN town hall event Tuesday that needs to change.

"I saw that Speaker (Paul) Ryan said some things tonight about getting to the bottom line," Kasich said. "Frankly, I think he should be more aggressive. I think he should speak out more and hopefully he will."

A spokesperson for Ryan released a statement earlier Tuesday night, saying: "We need to have all the facts, and it is appropriate for the House Oversight Committee to request this memo."

Comey hearing?

A Comey hearing would instantly become one of the most significant congressional appearances of modern times.

The practiced, analytical note-taking of a former FBI director who knows how to leave a paper trail would amount to a compelling piece of evidence in the court of public opinion and pit Comey's word against Trump's.

After all, a Comey memo could approach "smoking gun" significance if it appears to prove that the President could conceivably be accused of obstructing justice -- potentially grounds for impeachment.

A Comey appearance before a high wattage, televised hearing would mark another extraordinary dimension in a career in which the former FBI chief has found himself at the center of gripping episodes of Beltway drama.

Ten years ago, Comey, then acting attorney general, rushed to a Washington hospital to thwart an attempt by White House counsel Alberto Gonzales and White House chief of staff Andy Card to get a seriously ill Attorney General John Ashcroft to reauthorize a surveillance program.

That intervention made him a hero for Democrats. But they came to despise Comey for his leading man role in a later drama, the probe into Hillary Clinton's email server.

Clinton's campaign blames Comey for her defeat last November. He intervented late in the campaign over a new batch of emails found on the laptop of Anthony Weiner, the husband of the Democratic nominee's aide Huma Abedin.

Trump lauded Comey for his conduct. But he soon came to loggerheads with Comey in his own administration, when the FBI director reportedly refused to offer him a vow of loyalty. Tuesday's reports that the President tried to get him to shelve the Flynn probe only thicken the plot.

Comey's political misadventures may offer Republicans a chance to question his motives should he testify, and the GOP is in a mood to defend its president, whose antics in recent days have sorely tested the patience of his supporters.

Falsehoods, exaggerations and blatant untruths

But it is also possible that given his administration's history of repeated falsehoods, exaggerations and blatant untruths, on issues from the size of the inauguration crowds to claims that President Barack Obama wiretapped Trump Tower, the President may not come across as a particularly credible witness in the court of public opinion.

And there's no guarantee that the White House can get its story straight. In recent days, Trump has repeatedly contradicted his own press team as they work to defuse multiple firestorms in Washington.

Since Comey would testify from Congress, and Trump can command the bully pulpit, both men, in effect would be vying for victory in the court of public opinion.

Comey, in the very act of taking notes about his conversations with Trump, seems to have indicated that at the very least he considered the President a problematic character who could embroil him in future controversies.

Trump has already made clear his deep antipathy to Comey. After firing him, Trump told NBC News that the FBI director was a "showboat" and a "grandstander" whom he had been planning to jettison for months.

Those unflattering impressions are not likely to be improved if Trump, ever the showman himself, tunes in on cable television to watch Comey starring in a hearing that keeps the rest of the country on tenterhooks.

But the result of their public duel may go a long way to dictating the fate of Trump presidency. If Trump allies fail to paint Comey as a discredited figure, he could impose deep political damage on the President.

It was already immediately noticeable in the wake of Tuesday's disclosures that Republicans on Capitol Hill were more reticent about coming out in strong support of the President than they had been on previous occasions.

A damning performance by Comey could further add to their doubts and leave Trump in deep political peril if his alleged missteps persuade even a Republican Congress to contemplate impeachment proceedings.

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