Despite Donald Trump's aides and lawyers reportedly pleading that he give his often damaging tweets a rest, there's an expectation he'll try to duke it out with Comey in real time - tweeting his immediate thoughts as Comey speaks in what is being billed as a political Super Bowl.

By various accounts, Trump is seething; defiant and frustrated; spoiling for a fight; and all the time chaffing at advice that he should restrain himself.

And on Wednesday evening, Washington time, Trump might have felt less so because at Comey's request, the Senate Intelligence Committee released his dramatic opening statement. It appeared to be a calculated bid to steal a march on a Trump counter-attack, which is scheduled to kick in after Comey's appearance.

"He's infuriated at a deep-gut, personal level that the elite media has tolerated [the Russia story] and praised Comey," former House speaker Newt Gingrich told The Washington Post. "He's not going to let some guy like that smear him without punching him as hard as he can."

The White House claims that Trump will be busy making America great again on Thursday, but his public diary is clear all morning

save for one speech that will deprive him of Twitter time.

"He's not going to take an attack by James Comey laying down," said Roger Stone, a Trump friend and informal political adviser. "Trump is a fighter, he's a brawler and he's the best counter puncher in American politics."

But at the West Wing anxiety reigns. White House counsel Donald McGahn has unnerved staff by ordering them to hold onto all emails, documents and phone records that might be sought by investigators.

At the same time, they're facing challenges in building Trump's defences.

Plans for a "war room" to counter what Trump calls "this Russia thing" have fallen in a heap as top-flight legal brains have refused to join the fight to protect the President.

Also, a roster of Trump surrogates who will fan out on the airwaves after Comey's testimony is said to be devoid of any real political star power and the Trump loyalists who might join them are complaining they have been given no talking points.

As Trump girds to fight, the extent to which he's being boxed in by events was evident in his reported response to Jeff Sessions threatening to resign late last month.

Trump would like to see the back of his attorney-general.

But if he allowed the former Alabama senator to walk, Trump would have difficulties winning Senate confirmation for his replacement; and that would leave him with Rod Rosenstein, Sessions' deputy, as acting attorney-general - and Rosenstein is not flavour of the month at the White House because it was he who acted unilaterally to appoint a special counsel to investigate the whole Russia business.

On Wednesday, there was further evidence of the challenge Trump faces in pushing back in the face of a wave of damaging leaks. Just as Comey confirms much of what has been reported, a parade of still serving national security officials came before Congress and went without firmly knocking down the leak-based reports.

When Dan Coats, the director of national intelligence, was asked about a report that Trump had urged him to get Comey to drop the Flynn investigation; and when Michael Rogers, the head of the National Security Agency, was quizzed on a report that Trump wanted him to deny the existence of any evidence of collusion with Russia, both men demurred, refusing to discuss the details of their interactions with Trump.

Stepping away from specifics, Rogers spoke in terms that might be described as a general denial. "I have never been directed to do anything I believe to be illegal, immoral, unethical or inappropriate," he said. Coats too spoke in similar terms.

Both men revealed the art of answers that are not answers. Or maybe they were - because in dodging the questions two of Trump's most senior national security officials left the reports, by The Washington Post, unchallenged at the same time as Washington was absorbing yet another Post report, elaborating on its earlier scoops with a more detailed account of conversations in which Coats is said to have revealed to associates that indeed Trump had put him under pressure.

Senators clearly were frustrated.

Senator Angus King, an independent from Maine, snapped at Coats: "You swore that oath to tell us the truth." And when King demanded the "legal basis" for Coats' refusal to answer questions, the national intelligence director replied: "I'm not sure I have a legal basis."

In a dramatic curtain raiser to his testimony before Congress on Thursday, Comey wrote a detailed account of Trump's insistent demand over dinner in January - "I need loyalty, I expect loyalty."

"I didn't move, speak, or change my facial expression in any way during the awkward silence that followed," Comey says in the statement that was released by the Senate Intelligence Committee.

"We simply looked at each other in silence. The conversation then moved on, but he returned to the subject near the end of our dinner."

From the get-go, Comey was troubled.

When Trump had called earlier in the day he had mentioned he was thinking of asking Comey's family, but had decided they might visit the White House another time.

Still, as Comey headed to the White House for the 6.30pm dinner on January 27, he figured others would be dining with them.

On finding himself alone with Trump in the Green Room, Comey writes: "My instincts told me ??? the dinner was, at least in part, an effort to have me ask for my job and create some sort of patronage relationship. That concerned me greatly, given the FBI's traditionally independent status in the executive branch."

Comey's concise, seven-page statement, tightly written but with a flair for drama, reveals a national security leader so wary of pressure from his President that he adopted a new practice of immediately recording every such encounter.

Comey's statement confirms the accuracy of much that has been leaked.

Comey briefed the President on allegations of salacious conduct by Trump during a 2013 visit to Moscow - and the President denied he had been "involved with hookers in Russia". It also confirmed Trump's request that the FBI drop its investigation into disgraced former National Security adviser Michael Flynn.

Additionally, it detailed Comey's plea to Sessions to block Trump's orchestration of one-on-one meetings with Comey. Crucially, it contains Trump's demands that Comey act to "lift the cloud" of the Russia investigations.

But he also confirms a Trump claim that has been questioned - as FBI director, he had advised Trump that he, personally, was not under investigation.

Comey does not use the term "obstructing justice," an explosive accusation against Trump that is expected to dominate questions from the Senate Intelligence Committee, when Comey makes his much awaited appearance on Thursday - his first in public since Trump sacked him on May 9.

But publication of the Comey statement has some pundits joining the dots to make an obstruction charge - (1) Trump demanded loyalty; (2) he told or directed Comey to wrap up the Flynn investigation; (3) he sacked Comey when Comey refused to close the Russia investigation; and (4), Trump admitting on national television that the reason he fired Comey was because of the Russia investigation.

With Comey's opening statement as prologue, all eyes turn towards Washington.

So TV addict that he is, Trump will surely be tuning in to Comey, too.

"He believes in the long run there is an enormous premium on being the person who stands there fighting," said Gingrich, who is soon to publish his book, Understanding Trump.

"People respond to that and wonder if he's fighting this hard, maybe he's right and the other guys are wrong. It's the core of how he operates."

It's all a witch hunt, Trump insists.

But maybe that's an unfortunate metaphor, because a good witch hunt ends with someone getting burnt.