WASHINGTON — President Donald Trump gave embattled GOP Senate candidate Roy Moore a vigorous formal endorsement Monday, looking past allegations of sexual misconduct with Alabama teenagers as Republican leaders in Washington, once appalled by Moore’s candidacy, began to come to grips with the ever-clearer possibility of his victory.

Buoyed by the taste of his own success in Congress as the Republican tax bill inches closer to passage, Trump telephoned Moore to offer encouragement as well as support and also argued in a pair of tweets that Moore’s vote was badly needed to push the president’s policies forward.

In addition, Senate Majority Leader Mitch McConnell, who was initially among several national Republicans to urge Moore to drop out of the race, said Sunday it was up to Alabama voters to decide whether the former state Supreme Court chief justice should be elected.

Weeks ago, when accusations of sexual misconduct with teenagers first surfaced, Trump’s spokesman had said the president believed Moore would “do the right thing and step aside” if the allegations were true.

Top Republicans vowed to expel him from the Senate if he won his Dec. 12 special election. And, publicly and privately, GOP leaders described the allegations against Moore as credible and insisted there were no circumstances under which he should serve in the Senate.