The president asserted that Comey told him three times that he was not personally under investigation, while the former director's associates allege Trump asked Comey if he could back off an investigation into Michael Flynn, who was sacked as national security adviser because he misled the White House about his ties to Russian Federation.
But beyond devising a thorough and effective messaging strategy to deflect the steady stream of bombshell reports surrounding the federal investigation that have dogged the White House in recent months, the White House will still have to contend with a President who has frequently stepped on official messaging efforts in 140 characters or less. The White House said he had misled Vice President Mike Pence about contacts Flynn had with Russia's ambassador to the United States, Sergei Kislyak, before Trump took office.
The nonprofit Great America Alliance said Tuesday it would air an ad calling Comey "just another DC insider only in it for himself".
Comey also will try to steer clear of saying anything that could compromise or constrain the work of special counsel Robert Mueller, now heading up the investigation, such as offering legal or prosecutorial judgments, these people said.
Trump's White House and its allies are crafting a strategy aimed at undermining Comey's credibility.
The relationship between the attorney general and the president has grown increasingly tense since Mr Sessions recused himself from any involvement in the Russian Federation investigation, articles in the Washington Post, the New York Times, and Politico said. We need to start fighting back.
Still, Trump supporters say they are willing to step in to help the White House deflect any accusations from Comey.
London Bridge incident is 'potential act of terrorism', says Theresa May
One witness told the BBC it was possible some pedestrians had gone over the side of the bridge and into the Thames River below. Casualties were seen being taken away from Tito's restaurant on London Bridge Street with blood on the steps of the eatery.
"We're going to have an opportunity to ask him [Comey] questions and to do so in front of the American people in an open hearing", Rubio said. As important as that hearing was, the stakes - and the buildup - to Thursday's appearance are even bigger.
"Director Coats does not discuss his private conversations with the President".
"I assume they'll do the same thing with this", Rollins said of the Comey hearing. What matters in considering possible obstruction of justice, this source added, is the President's intent, not how Comey felt about it.
Republicans will be interested in whether he faced any pressure under the Obama administration to let Clinton off the hook. Sources say the parameters set by the two men - who are friends and former colleagues at the Justice Department - were aimed at avoiding the possibility that Comey's testimony could taint any criminal case that Mueller might ultimately bring.
Days after announcing in unusually public fashion the FBI's decision not to recommend charges in the Hillary Clinton email investigation, Comey faced more than four hours of often-contentious questioning about how he had reached his conclusion.
Acting FBI Director Andrew McCabe, who took over after Comey was sacked, will also be at the hearing.
With outside groups already rushing to try to control the narrative on Mr. Comey's first public comments on his firing, Republican lawmakers will likely challenge his credibility while Democrats will push the former Federal Bureau of Investigation director to detail Mr. Trump's private conversations, including the president's claims that Mr. Comey repeatedly told him he was not a target of the Federal Bureau of Investigation probe into Russian hacking charges. With Trump are from left, Senate Majority Leader Mitch McConnell of Ky., House Speaker Paul Ryan of Wis., and Senate Majority Whip John Cornyn of Texas.