Democrats scored a sweeping victory in the US midterm elections, capturing both the House of Representatives and the Senate in a result that exceeded expectations.

The party flipped key seats in states including Maine, Iowa, the Carolinas and Kansas, where a Democrat won a Senate race for the first time in nearly a century.

Democrats also celebrated major gains in Texas, unseating the Republican governor and winning a Senate seat.

The results deal a significant political blow to President Donald Trump.