Republican control could be a moderating force on Mr Trump. The Senate has welcomed more right-populist Republican members like Mr Moreno in recent years, but still remains a bastion of pre-Trump conservatism. A narrow Republican majority in the Senate could empower moderates to reject Trump nominees outside the political mainstream.

The Republican Party has won the U.S. Senate majority, regaining control for the first time in four years, but who will win the House?