Florida is once again at the center of election controversy with the state's high profile Senate and governor races – which looked to be heading into Republican hands – set for mandatory recounts.

The development is one of several that suggest the basis for President Donald Trump's claim Tuesday's midterms were a "tremendous success" for his party was premature.

Trump argued that the Republican performance in Senate races meant the midterm elections were a win for his party despite a heavy defeat in the House of Representatives and the loss of at least six governor's mansions.

When the president gave a combative press conference on Wednesday it appeared the Republicans could open up a majority of eight in the upper chamber – now the margin could be as low as two.

The Republicans flipped three seats and lost one, but three are yet to be decided. With Mississippi set for a runoff election, Florida in the balance and Arizona leaning Democratic, it remains possible that the Republican majority in the Senate will remain unchanged at 51-49.

The two undeclared as yet gubernatorial races favor the Republicans, but there will be a recount in Florida and could be a runoff in Georgia. The Democrats gained 32 seats in the House with 10 still to be declared.

Florida drama

Republicans Rick Scott and Ron DeSantis looked set for victory in Florida's Senate and governor contests respectively on election night, but votes are still being counted and each man's lead has fallen below the 0.5 percent threshold which triggers an automatic recount.

Outgoing governor Scott holds a lead of around 12,500 votes – 0.15 percent – over Democratic incumbent Bill Nelson with around 8.2 million votes cast in the Senate election, and Republican DeSantis leads Andrew Gillum by around 33,700 votes – 0.41 percent – in the gubernatorial race.

Both Republicans declared victory on election night and Gillum conceded the gubernatorial race, but votes are still being counted in the Democrat-leaning Broward and Palm Beach counties.

Trump and Scott both alleged – without evidence – that attempts were being made to "steal" the election.

Trump, in Paris for ceremonies to mark the 100th anniversary of the end of the First World War, tweeted: "Trying to STEAL two big elections in Florida! We are watching closely!" Scott tweeted that “we won't let liberal activists from all over the country come to Florida and steal this election.”

Slow vote counting is not unusual in the US, but becomes a headline issue in a neck-and-neck election.

Gillum, who is vying to be Florida's first African-American governor, on Saturday withdrew his concession and made an "uncompromised and unapologetic call that we count every single vote."

Nelson said he would fight to ensure every vote was counted, and added in a statement that he believes "when every legal ballot is counted we'll win this election."

2000 rerun?

Machine recounts are expected to take several days, with a deadline of 15:00 on Thursday. Official results, which would include manual recounts, are due on November 18.

However, in scenes reminiscent of the controversial 2000 presidential election, a series of legal challenges have already been made. Both the Republicans and Democrats have sent teams of lawyers to Florida and the drama could yet drag on for weeks.  

George W. Bush was declared the winner over Al Gore by 537 votes in Florida in 2000 when the Supreme Court ordered a recount to end after over a month of deadlock, sending Bush to the White House.

A third recount will be held in the statewide election for Florida's next agriculture commissioner, with the Democrat candidate holding a lead of around 5,000 votes.

Arizona, Georgia, Mississippi

Several other midterm races are yet to be declared, including in Arizona where Democrat Kyrsten Sinema has established a lead over Republican Martha McSally in the battle to replace Jeff Flake in the Senate.  

Sinema's lead had widened by Saturday evening to about 23,900 votes, or 1.17 percent, with up to 370,000 ballots yet to be counted.  

Republican Brian Kemp declared victory on Wednesday in Georgia's gubernatorial election with a narrow lead. He has since resigned as secretary of state, a role in which he oversaw the state's electoral system, and begun the transition process to be governor.

However, with votes yet to be counted Kemp sits on 50.3 percent of the vote – if he falls below 50 percent a runoff against Democrat Stacey Abrams will take place. Abrams' campaign has vowed to take legal action to ensure all ballots are counted amid claims the Democrat vote was suppressed.

In Mississippi, a runoff will take place on November 27 between Republican Cindy Hyde-Smith and Democrat Mike Espy after neither secured above 50 percent of the vote.