The US holds its midterm elections on 8 November 2022. Photo: 123RF
The United States holds its midterm elections on 8 November 2022. The outcome will have a major impact on the remaining two years of Joe Biden's presidency, and beyond.
The results will begin coming in tomorrow afternoon New Zealand time.
* Live: RNZ will live blog the US midterms from about 11am Wednesday.
Here's what you need to know.
What are the midterms and who's being elected?
These elections are for Congress, which is made up of two parts - the House of Representatives and the Senate.
These votes are held every two years and when they fall in the middle of the president's four-year term of office, they are called the midterms.
Congress makes nationwide laws. The House decides which laws are voted on while the Senate can block or approve them, confirm appointments made by the president and, more rarely, conduct any investigations against him.
Each state has two senators, who sit for six-year terms. Representatives serve for two years, and represent smaller districts.
All the seats in the House of Representatives are up for election in November, alongside one-third of the Senate.
Several major states also have elections for their governor and local officials.
Who might win?
The Democratic Party has held the majority in both the House and the Senate for the past two years. That's been helpful for President Joe Biden to pass the laws he wanted.
But the Democrats hold that power over the Republicans by very narrow margins, which makes for a tight contest. Polling suggests the Republicans might take the House but the Democrats could hold on to the Senate.
Of the 435 seats in the House, most are safely held by either party, with just 30 currently a toss-up between the two. Suburban areas around cities in states like Pennsylvania, California, Ohio and North Carolina will be key.
In the Senate, it now looks like four of the 35 seats being contested realistically could go either way. The pivotal races here are in Nevada, Arizona, Georgia and Pennsylvania.
With so many races expected to be very close, it could take days before we have the final results.
What are the big issues?
At the start of 2022, it looked like the biggest issues were going to be immigration, crime and the cost of living, which are vote-winners for conservative Republicans.
That changed in June when the US Supreme Court overturned national abortion protections, giving a boost to the Democrats, who support women having the right to choose and have made that central to many campaigns.
But as the immediate impact of that decision fades, Republicans are trying to turn the focus back to inflation, immigration and violent crime.
What effect will the results have?
Midterms often serve as a verdict on how the president is doing, and the party that holds the White House tends to lose seats.
That's a worry for President Biden, whose approval rating among voters has been running at less than 50 percent since last August.
If the Democrats hang on, President Biden will be able to keep going with his plans on climate change, to expand government-run healthcare programmes, protect abortion rights and tighten gun control.
If the Republicans take control of either chamber, they will be able to effectively grind that agenda to a halt.
They will also be able to control investigatory committees, so they could end the inquiry into the 6 January 2021 attack on the US Capitol by supporters of former President Donald Trump - although its work is set to finish by the end of the year.
They might also launch new investigations into more conservative-interest topics - like the Chinese business dealings of Joe Biden's son or the sudden withdrawal of US troops from Afghanistan.
It would be harder for Biden to make new appointments, including to the US Supreme Court. Republican dominance would also hamper his foreign policy - particularly help for Ukraine, as it battles Russian invasion.
In return, President Biden could wield his veto pen and block conservative laws on abortion, immigration and taxes.
The result? Gridlock until the next presidential and congressional elections.
How does this shape the 2024 presidential race?
The midterms could give us a clue as to who might be in the running to be the Republican presidential candidate for 2024.
If candidates backed by Trump do badly, he's less likely to get backing from the Republican party to run for president again. In Florida and Texas, Republican governors Ron DeSantis and Greg Abbott hope re-election will spur them on to a bid for the White House.
If the Democrats can hold on to power in Michigan, Wisconsin and Pennsylvania, that should give them some confidence as they build their 2024 campaign to get President Biden re-elected.
- BBC