The chamber will play a huge role in not only legislative priorities next year, but also the incoming president’s ability to pick a Cabinet.

WASHINGTON—Republicans seized control of the Senate and looked in position to narrowly keep power in the House, setting President-elect Donald Trump up to more easily confirm nominees and muscle through key priorities on taxes and other issues.

Republicans have taken control of the U.S. Senate and are fighting to keep their majority in the U.S. House, which would produce a full sweep of GOP power in Congress alongside