US President Donald Trump has pressed the Republican governor of Georgia to help overturn Joe Biden's presidential election victory in the state, BBC News reported.

In a series of tweets, Trump urged Georgia governor Brian Kemp to call a special session of the state legislature.

It came before the incumbent president attended a campaign rally in Georgia for upcoming Senate runoff elections.

Georgia was a key battleground state in the election and Joe Biden's narrow win—the first time the state had voted Democrat since 1992—helped to seal his victory.

It is now the focus of an intense political battle for control of the Senate. If Democrats win January's two runoff elections there, Republicans would lose control of the upper house.

According to the Washington Post, Trump called Kemp on Saturday morning and asked him to demand an audit of absentee ballot signatures. Kemp—who has no power to order such an audit—turned down the requests, a source told the newspaper.

Then on Twitter, the president turned up the pressure on the Georgia governor.