Americans vote in congressional elections for the full House of Representatives and just over a third of the Senate. According to most forecasts, the Republicans will win the House of Representatives, while the situation in the Senate is uncertain.

Called midterm elections, since they take place halfway through a presidential term, they are also traditionally a kind of referendum on the current president, and almost as a rule, the party in power in the White House loses power in Congress in the inter-election period.

In the current session of the House of Representatives, the Democrats have a small majority (222 to 213) and it is almost certain that they will now lose it.

The Republican Party is on its way to taking control of the US House of Representatives, while Democrats are currently leading the Senate race according to preliminary election results.

Republicans currently have 198 seats and Democrats 173 in the House of Representatives, according to US television projections. A majority in this chamber requires 218 mandates.

In the battle for the upper house, the Senate, the current balance of power is 48-48.

Democrats were given a boost by John Fetterman's victory over TV doctor Mehemet Oz in Pennsylvania, one of the key states for the election.

Races are still open in four states besides Georgia, namely Arizona, Nevada and Wisconsin.

Former Republican congressman Joe Walsh predicts that former President Donald Trump could be impeached if Democrats retain control of the Senate, but Republicans are unlikely to admit that publicly.

"Privately they're going to do what they've done for the last six years because they're all cowards, privately they're all going to blame Trump. None of them are going to say that publicly, they're going to publicly blame anybody but Trump and I hope once again that Trump just goes away," Walsh told the BBC.

Walsh said it was a good night for Democrats. "Democrats look set to retain control of the Senate and may only lose a few seats in the House."

"This is a big win," he says, adding "although he will probably lose control of the House."