PRESIDENT Donald Trump has thrown his full support behind embattled Republican US Senate candidate Roy Moore who faces allegations of historical child sex abuse.

It comes as Republican leaders in Washington, once appalled by Moore’s candidacy, began to come to grips with the ever-clearer possibility of his victory and offered their backing.

Trump phoned Moore to offer encouragement as well as support. He also argued in a pair of tweets that Moore’s vote was badly needed to push his policies forward. The Republican National Committee quickly followed suit, announcing they were returning the support they had pulled last month.

In addition, Senate Majority Leader Mitch McConnell, who was initially among several national Republicans to urge Moore to drop out of the race, said 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, 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 December 12 special election. Republican party leaders insisted there were no circumstances under which he should serve in the Senate. But Moore has doggedly remained in the race.

In the phone call, Moore said, Trump offered “his full support and said he needs a fighter to help him in the US Senate”.

Moore tweeted that the president told him: “Go get ’em, Roy!”

A Republican National Committee official confirmed that it would once again be supporting Moore, after severing its fundraising ties to his campaign last month.

A Moore victory would set up a potentially explosive clash with fellow Republicans in Congress, some of whom have resoundingly called on him to quit.

Moore’s campaign was wounded by accusations of sexual misconduct, decades ago, made by women who were then teenagers. One woman alleges he initiated sexual contact when she was 14.

Moore denies it all.