WASHINGTON—President Trump intends to nominate the head of the country’s largest organization of police officers to lead the Bureau of Alcohol, Tobacco, Firearms and Explosives.

Chuck Canterbury is currently president of the national Fraternal Order of Police and has been a guest of the White House at a number of law enforcement events. ATF has been without a Senate-confirmed leader since Mr. Trump took office. Currently half of the 10 biggest federal law agencies lack permanent chiefs.

Mr....