WASHINGTON — Matt Gaetz withdrew Thursday as President-elect Donald Trump’s pick for attorney general amid continued fallout over a federal sex trafficking investigation that cast doubt on his ability to be confirmed as the nation’s chief federal law enforcement officer.

The announcement averts what was shaping up to be a pitched confirmation fight that would have tested how far Senate Republicans were willing to go to support Trump’s Cabinet picks. It represents a setback in Trump’s efforts to install fierce loyalists in his administration and is the first indication of the resistance the incoming president could face within his own party to picks with checkered backgrounds.

“While the momentum was strong, it is clear that my confirmation was unfairly becoming a distraction to the critical work of the Trump/Vance Transition,” Gaetz, a Florida Republican who one day earlier met with senators in an effort to win their support for confirmation to lead the Justice Department.

“There is no time to waste on a needlessly protracted Washington scuffle, thus I’ll be withdrawing my name from consideration to serve as Attorney General. Trump’s DOJ must be in place and ready on Day 1,” he added.

Trump, in a social media post, said: “I greatly appreciate the recent efforts of Matt Gaetz in seeking approval to be Attorney General. He was doing very well but, at the same time, did not want to be a distraction for the Administration, for which he has much respect. Matt has a wonderful future, and I look forward to watching all of the great things he will do!”

The selection of Gaetz just nine days ago to lead the department that once investigated him came even as Trump was thought to be considering other contenders with more extensive legal qualifications. In the Senate, deeply skeptical senators repeatedly raised concerns over the sex trafficking allegations and demanded more information about a now-closed federal investigation. Meanwhile, Justice Department lawyers were taken aback by the pick of a partisan lawmaker who has repeatedly railed against their agency and echoed Trump in claiming that it had been weaponized against political adversaries.

In recent days, an attorney for two women said his clients told House Ethics Committee investigators that Gaetz paid them for sex on multiple occasions beginning in 2017, when Gaetz was a Florida congressman.