Kash Patel, President Trump’s pick to run the F.B.I., repeatedly evaded the question of whether he would investigate officials on a published list of his perceived enemies during his confirmation hearing on Thursday, even as he sought to allay fears about his fitness to serve and his fealty to President Trump.

In trying to distance himself from far-right associates and his own statements, Mr. Patel, a cocky and confrontational Trump loyalist, suggested he disagreed with Mr. Trump’s decision to pardon Jan. 6 rioters who attacked law enforcement officials. It was a rare divergence from a president who selected him to run the nation’s most powerful law enforcement agency.

Asked if he agreed with Mr. Trump’s broad grant of clemency on the day he was inaugurated, Mr. Patel, a former congressional staff member and national security aide, said he had “repeatedly, often publicly and privately, said there can never be a tolerance for violence against law enforcement.”

The nomination of Mr. Patel, 44, has upended the post-Watergate tradition of picking nonpartisan F.B.I. directors with extensive law enforcement experience. If confirmed, Mr. Patel could provide Mr. Trump with a direct line into the bureau, possibly eliminating guardrails meant to insulate it from White House interference.

While the hearing addressed a range of issues stemming from Mr. Patel’s actions and statements, Democrats time and again accused Mr. Patel of prioritizing his allegiance to Mr. Trump over adherence to the rule of law, a charge the nominee forcefully denied.

When Senator Mazie K. Hirono, a Hawaii Democrat, asked if he planned to investigate the former F.B.I. director James B. Comey and others he has attacked publicly, Mr. Patel said he would abide by the law and the Constitution and would scrutinize only those he deemed likely to have committed crimes.