WASHINGTON—Donald Trump has chosen Kash Patel to be Federal Bureau of Investigation director, moving to force out the bureau’s current leader, Christopher Wray, before the end of his 10-year term in favor of a fierce loyalist who has promised to upend the nation’s premier law-enforcement agency.

President-elect Donald Trump announced Saturday his intention to appoint Kash Patel, a former chief of staff to the acting secretary of defense during Trump’s first term, as the next director of the Federal Bureau of Investigation (FBI).

The president-elect plans to replace current FBI Director Christopher Wray with Patel, a close ally of the president-elect and former national security aide, has berated the Justice Department and the news media.