The Democrats' hopes of winning control of the US Senate have been dealt a blow in the mid-term elections.
A Donald Trump Republican ally is projected to unseat an incumbent in Indiana, but Democratic senators held on in West Virginia and New Jersey.
Democrats also scored significant gains in the House of Representatives, and two US networks predict they will take control of the chamber.
Republicans currently control both legislative chambers.
President Trump is not up for re-election until 2020, but Tuesday's poll will shape his agenda for the remainder of his two years in office.
What's happening in Senate races?
Republicans look likely now to retain control of the Senate - they currently have a slim 51-49 majority, but only nine of the party's seats were up for grabs, while Democrats were defending 26 seats.
Republican businessman Mike Braun was projected to oust first-term incumbent Joe Donnelly, a moderate Democrat in Indiana.
White House press secretary Sarah Sanders said Mr Trump had "closed the deal" for Mr Braun after holding a rally in the state on Monday night.
Republican Marsha Blackburn won a Senate seat in Tennessee against Democrat Phil Bredesen, who was endorsed by pop star Taylor Swift.
There was some consolation for Democrats as Senators Joe Manchin and Bob Menendez held on to their seats after tough campaigns in West Virginia and New Jersey respectively.
Mr Manchin was the only member of his party to vote to confirm Supreme Court Justice Brett Kavanaugh, whose nomination narrowly survived sexual assault claims.
A cliff-hanging vote count in Florida has Republican Rick Scott neck and neck with incumbent Democratic senator Bill Nelson.
Republican Ted Cruz Cruz has a slight lead against his challenger, Democratic rising star Beto O'Rourke.
Mitt Romney, the 2012 Republican presidential nominee, has won election to US Senate from Utah, as expected.
Two US networks - Fox and NBC - are projecting that the Democrats are expected to win the 23 seats they need to take over the House of Representatives.
Americans voted for all 435 seats in the House.