Democrats or Republicans: When will we know the results of US midterm elections?

US Midterm Elections 2022: The earliest vote tallies will be skewed by how quickly states count mail ballot.

It seems like it will be a long night and probably days of waiting before it is clear whether Democrats or Republicans will control Congress following the US midterm elections.

US Midterm Elections 2022: A sign reading "Vote Here Today" sways in the wind outside a polling station. (AFP)

As all 435 seats in the US House of Representatives are up for grabs along with 35 US Senate seats, election forecasters and opinion polls suggest Republicans have a very strong chance of winning a House majority. After the polls close, there could be declarations of victory but as many races are expected to be close, here's how the results for the elections will unfold:

1. The earliest vote tallies will be skewed by how quickly states count mail ballots- most Democrats vote by mail more often than Republicans.
2. The first wave of vote tallies are expected overnight and an early indication of success could come if the races are close.
3. The final results are unlikely to be completely clear as officials across US have warned that elections may drag on for days or weeks.
4. The delays could be due to many factors including close margins between candidates, potentially contested elections and the possibility of recounts.
5. Delays may also occur as various US states have varied rules for how mail-in ballots are counted and when.
6. The delay of results has been a politically contentious issue since the 2020 presidential election, when former president Donald Trump attempted to claim victory the following morning while votes were still being tallied.
7. As of Monday, more than 40 million early votes have been cast- including in-person and mail-in ballots.