Senior election officials in Georgia are now saying there will almost certainly be a run-off race for the Senate seat in early December.

That's because under the state's law, if no candidate gets more than 50% of the vote, it triggers a run-off between the top two candidates.

Former American Football star Herschel Walker, who's received the backing of Donald Trump, is battling incumbent Raphael Warnock, who preaches at Martin Luther King Jr's former church in Atlanta.

Georgia is a key seat that could be pivotal for either the Democrats or Republicans to control the Senate.

Election official Gabriel Sterling has tweeted that while "detailed work on counting votes" is continuing "we feel it is safe to say there will be a runoff for the US Senate".