Republicans thwarted Democratic efforts to retake the US Congress during the historic election, using a show of conservative force to maintain control of the Senate and House of Representatives.

The Senate was in Republican hands, 54 to 46 and in danger of sliding into Democratic control. But they rallied to minimize their losses, with incumbents in the battleground states of Pennsylvania, North Carolina and Wisconsin snatching crucial victories.

In the House, Republicans were on track to take 239 seats to the Democrats' 196, according to NBC's House model.

That would be an eight-seat gain for Democrats, but still well short of what would be necessary to snatch the 435-member chamber back from Republican control.

“This could be a really good night for America,” House speaker Paul Ryan, who won a 10th term in Wisconsin, told supporters in his home town of Janesville.

The Democrats needed to turn over the GOP’s 54-46 Senate majority in what ought to have been a vulnerable year for the Republicans, who were defending 24 seats compared to the Democrats’ 10.

Former 2016 presidential hopeful Marco Rubio overcame Democratic challenger Patrick Murphy to keep his Senate seat in Florida, while John McCain, the 80-year-old Arizona Senator who lost the 2008 presidential race to Barack Obama, comfortably defeated Democratic Congresswoman Ann Kirkpatrick to ensure he will serve another term in Washington.

House members serve two-year terms, while Senators are elected for six years.

With Mr Trump claiming the White House and Republicans keeping control of both houses of Congress, it puts the US on the brink of sweeping legislative change, with both Mr Trump and Mr Ryan in a position to pass their policy agendas without any Democratic opposition.