Washington DC - The balance of power in the US Congress was hinging on the outcome of a small handful of knife-edge races, as Republicans appeared poised to flip at least one chamber despite an overall disappointing midterm election for the conservative party.

The election will decide who will call the shots in Congress and what President Joe Biden, a Democrat, can still do politically in the next two years before the 2024 presidential poll, which former Republican president Donald Trump is expected to contest.

A clearer picture of Tuesday's election was emerging as results came in from several closely fought races. Democrats currently control both the House of Representatives and the Senate.

By Wednesday it was obvious that three states – Arizona, Georgia, and Nevada – were set to determine control of the Senate.

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This year, 35 of the 100 Senate seats were contested. The current Senate is split 50-50, with Vice President Kamala Harris able to cast a tie-breaking vote for the Democrats.

There was still the possibility that Biden's Democrats could defy the historical odds for midterm elections – which typically favor the party out of power – and hold on to the upper chamber.

As of Wednesday afternoon, US networks said Democrats had taken 48 Senate seats and Republicans 49.

Georgia was set to go to a run-off in December as neither Democratic Senator Raphael Warnock and Trump-backed former football star Herschel Walker achieved more than 50% of the vote, according to network projections.

But the outcome of Georgia run-off may not matter as to the control of the Senate. If Republicans are successful in both Arizona and Nevada, then they will take power. A significant number of votes were yet to be counted in those states.

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Meanwhile, Republicans were on track to retake the 435-seat House of Representatives, but by smaller-than-expected numbers than experts had forecast.

Broadcaster CBS projected Democrats as so far having won 200 seats and Republicans 210 – both of them still short of the 218 needed for a majority.

Even if they do end up narrowly winning a majority in both chambers, Republicans may have a hard time keeping their own ranks together as the critical 2024 election nears. The party appears increasingly torn between radical Trump acolytes and those who want to put the uncontrollable former reality TV star behind them.

Trump endorsed candidates by the dozen during the campaign, but election night showed that Trump's influence as a kingmaker has its limits.

Some particularly flamboyant and sometimes radical candidates he aggressively supported wound up losing, including controversial TV doctor Mehmet Oz, for example, who ran against Democrat John Fetterman for a Senate seat in Pennsylvania.

Or Pennsylvania gubernatorial candidate Doug Mastriano, an ardent Trump supporter who spread election fraud fantasies.

Governors can wield significant power in elections, as they are involved in confirming presidential results in the United States.

Trump is expected to announce his presidential bid for 2024 in the coming week, after several days of not-so-subtle hints in that direction. He said it was "very, very, very probable" at a recent rally.

But one Republican election result in particular could be a bad omen for Trump: the massive win of his biggest intra-party rival, Ron DeSantis, in the Florida governor's race. His walloping win over the Democratic candidate in the state that has outsized influence in US politics was seen as a signal of his popularity.

DeSantis is viewed as one who could run against Trump within the party for the 2024 presidential race. Increasingly in the national spotlight, DeSantis is a hardliner with Trump-like positions but without the political and legal baggage of his party colleague. According to some critics, DeSantis is more dangerous than Trump because he is seen as more strategic, more thoughtful, and smarter.