President Trump is expected to nominate a replacement for fired FBI Director James Comey "in the coming days," a senior White House official told Fox News late Tuesday.

The official did not specify how soon Trump would nominate someone for the position. The official also did not indicate who was being considered for the position, but told Fox News to expect candidates who were non-political and could restore credibility to the position.

Here are some possible candidates to run the storied law enforcement agency:

-- RAY KELLY: The longest-serving police commissioner in New York City, Kelly oversaw the force in the years following the Sept. 11 attacks when terror threats were routine. His tough-on-crime stance, including support for provocative tactics like stop-and-frisk, could make him a natural ally of Attorney General Jeff Sessions and a go-to-guy for a fellow New Yorker like Trump. Kelly as commissioner defended a police operation that conducted secret surveillance of Muslims. He could partner with Trump and Sessions on anti-terrorism efforts.

-- CHRIS CHRISTIE: Though his relationship with Trump has been topsy-turvy, the governor of New Jersey has known the president for years and could bring law enforcement bona fides to the job. Christie is a former Republican-appointed United States attorney in New Jersey, and he cited that background time and again during his 2016 presidential campaign. His legacy as governor took a hit, however, with a so-called "Bridgegate" scandal that was investigated by the FBI, prosecuted by the Justice Department and which brought down some of his allies.

-- DAVID CLARKE: A wild-card, but the outspoken and polarizing Milwaukee County, Wis., sheriff has been a fierce supporter of Trump and even landed a speaking spot at last summer's Republican National Convention. That support has been cited as media outlets and pundits floated him as a possible Comey replacement overnight. A conservative firebrand known for his cowboy hat, Clarke has called himself "one of those bare-knuckles fighters" and has been critical of what he called the "hateful ideology" of the Black Lives Matters movement. But he'd be a long shot given that a county jury recently recommended criminal charges against seven Milwaukee County jail staffers in the dehydration death of an inmate who went without water for seven days.

-- TREY GOWDY: The South Carolina Republican led the House committee investigation of former Secretary of State Hillary Clinton's actions surrounding the deaths of four Americans in Benghazi, Libya. Gowdy is also a former federal prosecutor who boasts of his work on drug trafficking, bank robberies and child pornography cases. He was among lawmakers critical of Comey's decision not to prosecute Clinton in the email server investigation, saying other government officials would have been prosecuted if they handled classified information like Clinton did, but federal officials disagree with that assessment. Gowdy said after Comey's firing that though he had differences with the former FBI director on some matters, he "never lost sight of the fact that he had a very difficult job."

Fox News' Serafin Gomez and The Associated Press contributed to this report.