In his first campaign rally since he lost to Democrat Joe Biden in the Nov. 3 presidential contest, the Republican Trump reminded the chanting crowd that he came to southern Georgia to persuade them to vote Republican in runoffs on Jan. 5.

But he quickly turned to his repeated claims, made without evidence, of widespread fraud in the presidential election.

"They cheated and rigged our presidential election but we'll still win it. And they are going to try to rig this election too," Trump told the crowd, who chanted "We love you!" and "Four More Years!"

The outgoing president's claims have been rejected by state and federal officials across the country, and his campaign's numerous legal challenges have almost all failed.

Biden was the first Democratic presidential candidate to win in Georgia since 1992. Statewide recounts, including a painstaking review by hand of some 5 million ballots, turned up no significant irregularities.

Trump said on Saturday his challenge was headed to the US Supreme Court "very shortly," without elaborating. Legal experts do not see a path to the nation's highest court, however.

The January runoffs pit two Republican senators, David Perdue and Kelly Loeffler, against well-funded Democratic challengers Jon Ossoff and Raphael Warnock, seeking to capture a state that has not elected a Democratic senator in 20 years.

The races will determine which party controls the US Senate. Democrats, who already have the majority in the House of Representatives, need to win both seats to control the Senate. If Republicans win one seat, they will retain their majority and be able to block much of Biden's legislative agenda.

Biden said he would visit Georgia to campaign for the Democratic candidates but did not give a timetable for his trip.

Trump has attacked Republicans who have refused to back him, including Georgia's governor, Brian Kemp, and its secretary of state, Brad Raffensperger. Kemp did not attend the rally, one day after the death in a car crash of Harrison Deal, a close family friend of the governor and staffer for Loeffler.

Earlier on Saturday, Trump phoned Kemp and pressured him on Twitter to take further steps to benefit his bid to reverse the election results.

"I will easily & quickly win Georgia if Governor @BrianKempGA or the Secretary of State permit a simple signature verification ... Why are these two 'Republicans' saying no?" Trump wrote on Twitter.

After Kemp responded on Twitter that he had "publicly called for a signature audit three times," Trump said that wasn't good enough, and added in a second tweet that the governor should immediately call a special session of the state legislature.

"Your people are refusing to do what you ask. What are they hiding?" Trump said.

In a move unprecedented in modern US history, the Trump team has tried, without success, to get Republican-controlled legislatures in battleground states won by Biden to set aside the results and declare Trump the winner.

Biden won the election with 306 Electoral College votes - more than the 270 required - to Trump's 232. The Electoral College will meet on Dec. 14 to formalize the outcome.

Trump's penchant for making his political rallies all about him - and now, about his claims the US electoral system is rigged - has raised concerns among some Republicans that his appearance in Georgia could end up turning voters off or making them feel there is no point in voting.

Before the rally, Matt Towery, a former Georgia Republican legislator who is now a political analyst and pollster, said Trump could help if he praised the candidates, but warned:

"If he talks about them for 10 minutes and spends the rest of the time telling everyone how terrible Brian Kemp is, then it will only exacerbate things."