WASHINGTON (Reuters) - U.S. House Speaker Paul Ryan was unanimously nominated on Tuesday by his fellow Republicans for re-election as speaker in the new Congress next year, the House Republican Conference said on Twitter.

Ryan, who faced no challengers for the post from within Republican ranks, was nominated during a closed-door meeting of all Republican lawmakers in the House. He will face an election in January, when all members of the new House, both Democrats and Republicans, vote on a new speaker.

Republicans kept their majorities in both the House and Senate in the Nov. 8 elections in which voters elected Republican Donald Trump to the White House over Democrat Hillary Clinton.

"It is a tremendous honor to be nominated by my colleagues to serve as speaker of the House," Ryan said on Twitter. "Now it's time to go big."

Republicans also re-elected three other lawmakers to leadership positions: House Majority Leader Kevin McCarthy, House Republican Whip Steve Scalise, and the chairwoman of the Republican conference, Cathy McMorris Rodgers.

(Reporting by Susan Cornwell and Susan Heavey; Editing by Mohammad Zargham and Lisa Shumaker)