Christopher Asher Wray, 50, is scheduled to appear Wednesday before the Senate Judiciary Committee.
Wray was asked about emails released by the president's son Donald Trump Jr. detailing a meeting he had with a Russian lawyer he believed was offering opposition research into Hillary Clinton's campaign on behalf of the Russian government.
"Anybody who thinks I would be pulling punches as the Federal Bureau of Investigation director sure doesn't know me well", Chris Wray told the Senate judiciary committee in response to a question from committee Chairman Chuck Grassley.
Unlike the president, Wray supports Special Counsel Robert Mueller's investigation into possible coordination between Russian Federation and the Trump campaign.
Comey has testified Trump asked him for loyalty.
Wray, an assistant attorney general under President George W. Bush who now works as a lawyer in private practice, was nominated by Trump in June to lead the bureau.
Wray told Sen. Patrick Leahy, D-Vt., that no one had asked him for "any kind loyalty oath at any point in the process, and I sure as heck didn't offer one". His vows to pursue investigations regardless of political pressure, while standard, took on added significance as lawmakers digested news that Donald Trump Jr. and Jared Kushner met with a Russian lawyer during last year's campaign, contradicting repeated administration denials about election-year meetings with Russians. Wray said that no such demand had been made of him.
In 2004, Wray offered to team up with Comey, who was then the deputy attorney general, other DOJ officials and then-FBI Director Mueller in threatening to resign over concerns about George W. Bush's use of warrantless wiretapping.More news: Audio From Airport Incident
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In addition, once confirmed as the man to succeed the fired James Comey, in accordance with ethical standards, Mr Wray will have 90 days to dispose of stock he owns in an array of firms including Apple, American Airlines, Wal-Mart and Exxon Mobil -estimated to amount to millions of dollars.
After Trump dismissed Comey on May 9, the ex-FBI director said that the president had asked him to pledge his loyalty during a dinner at the White House months earlier.
Wray said that as a prosecutor, he learned about "playing it straight and following the facts wherever they may lead".
In a terse round of questioning by Graham, the South Carolina Senator pressed Wray on what our relationship to Russian Federation should look like.
Christopher Wray, now a private practice lawyer, worked under George W Bush's administration as assistant attorney general in the United States department of justice's criminal division between 2003 and 2005. He served the government at a time when harsh interrogation techniques were approved within the department for terror suspects captured overseas, though Wray said he was never involved in signing off on those methods.
Wray was very hesitant and visibly uncomfortable commenting on matters that are under ongoing investigation, including Comey's fateful press conference, which may have influenced the outcome of the 2016 election.
"My view is that torture is wrong", Wray said. He expressed confidence in Wray's ability to retain that independence.