“The FBI is one of our nation’s most cherished and respected institutions, and today will mark a new beginning for our crown jewel of law enforcement,” Trump said in a statement issued by the White House.

Here are some possible candidates:

— 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, exposed by The Associated Press, 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 Bridgegate scandal that was investigated by the FBI, prosecuted by the Justice and brought down some of his allies.

— DAVID CLARKE: A wild-card, but the outspoken and polarizing Milwaukee County, Wisconsin, sheriff has been a fierce supporter of Trump and even landed a speaking spot at last summer’s Republican National Convention. 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.”