After $421m spent, Georgia voters to go back to the polls

If you turned on a TV in the US state of Georgia any time in the past few months, you would probably see an ad for one particular election.

But after a long campaign and $421 million spent, voters are being asked to go back to the polls in a few weeks to choose a senator.

The run-off election between Democrat Raphael Warnock and Republican Herschel Walker on December 6 may well decide which party takes control in the Senate.

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At the current count, Republicans hold 49 seats and Democrats hold 48, with three still to be decided.

In Arizona, incumbent Democrat Mark Kelly has a four-point lead over Republican Blake Masters, but as more ballots are counted, that margin is closing.

And in neighbouring Nevada, Republican Adam Laxalt is two points ahead of Democrat Catherine Cortez Masto, but that margin is also closing.

If Democrats win both, they take the Senate.

If they only win one, all eyes will be on the Georgia run-off.

In any case, the run-off is expected to be a nasty and close affair.

Warnock finished the race with 49.2 per cent of the vote and Walker 48.7 per cent.

The run-off was triggered because neither candidate received 50 per cent of the vote.

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The question will be which party can get their voters to turn out for another election, after an already exhausting midterm.

In Walker's favour is the state's Republican lean, and Georgia's history of siding with the conservatives in run-off elections.

In Warnock's favour is the sheer unpopularity of Walker, who was dogged by multiple scandals during the campaign.

It was revealed during the campaign that Walker secretly fathered several children and allegedly pressured two women into getting abortions.

He has also been accused of lying about his academic record, his business successes and his ethnic background.

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Meanwhile, the House of Representatives is still very much up in the air.

At the current count, Republicans have won or are leading in 220 seats. Democrats have won or are leading in 215 races.

To take power in the chamber, a party needs 218.

But many ballots are yet to be counted, and it is entirely possible the leads in many of those seats could change.

In any case, whichever party takes power in the House will have a very tenuous hold on it.