What is at stake in the polls in the middle of President Donald Trump's administration?
2018 midterms: Everything you need to know about the US elections
Americans will vote on November 6 in what will be US President Donald Trump's biggest electoral test since he took office.
The US midterm elections are an unusual feature of American democracy and have the power to embolden or derail an administration.
Below is everything you need to know about the 2018 midterm elections:
What are people voting for on November 6?
US citizens will be voting to elect congressional members. Congress is made up of representatives and senators.
All 435 seats in the House of Representatives are up for election and 35 seats in the Senate are being contested.
The majority of state governorships are also at stake.
How does Congress work?
There are 435 seats in the House of Representatives elected on two-year terms. The number of seats per state are allocated according to population size.
There are 100 seats in the Senate, with each state receiving two seats. Senators serve six-year terms and a third of the Senate is elected every two years.
Together the House of Representatives and the Senate make up Congress, which is the legislative body of the United States.
The mix of term lengths and number of seats per state is designed to ensure the system is dynamic enough to change frequently and that small states aren't dominated by larger states and vice versa.
Why are the 2018 midterms important?
To pass a bill it must be approved by both the House and the Senate. Currently, the Republicans hold a majority in both chambers of Congress, but that could all change on November 6.
If the Democrats gain a majority in either the House or the Senate, they will be able to block Mr Trump's legislative agenda.
In order to make a law, the executive (the presidency) must work with and through the legislature (Congress). But if one of the two chambers of the legislature is politically opposed to the President's party, it is incredibly hard to pass laws, often resulting in legislative gridlock.
This is something Mr Trump's predecessor Barack Obama struggled with after the midterms in his first term.
The race for the House of Representatives
This is the race which could have the biggest impact on the state of US politics. For Democrats to take the house from Republicans they will have to gain 23 more seats than they did in 2016.
The election is far more dangerous for Republicans than it is for Democrats, according to The Cook Political Report. There are 44 Republican toss-up seats - where either party has a good chance of winning - but only three Democrat toss-up seats.
And there are 51 Republican likely seats - which have the potential to become engaged - and 10 Democrat likely seats.
The Democrats are likely to win a seat in New Jersey and three seats in Pennsylvania. Eleven more seats held currently by Republicans lean Democrat.
The race for the Senate
Out of the 35 seats up for election in November, there are nine seats that could go either way, five of which are held by the Democrats.
The Democrats only need to take two seats to retake control of the Senate, but there are only nine Republican seats up for grabs this year, most of which are expected to stay that way.
The Democrats' best chances of taking control of the Senate are in Arizona, Nevada, Texas and Tennessee.
As well as congressional elections, 36 out of 50 states will be electing governors. Of the 36, 26 of those governors are Republican.
Governors act as spokesmen for a state, oversee the passing of state laws and can appoint judges. They also play a big part in the raising of funds and drumming up support for presidential elections.
New governors in midterm elections could significantly influence presidential campaigns in 2019 and 2020.
Who is going to win?
This election is likely to be seen as a referendum on President Trump's presidency so far.
Historically, the party with the president in the White House has lost an average of 32 seats in the House of Representatives and two seats in the Senate at each mid-term election.
The Democrat's base is likely to be energised by the appointment of Brett Kavanaugh as a Supreme Court Judge. Mr Kavanaugh's appointment was mired in historical accusations of sexual assault and now polarises the Supreme Court to the right.
The opportunity to break the dominance Republicans have over all three branches of government is likely to be seized by a motivated Democrat base.
Additionally, Mr Trump low approval ratings indicate many of those who voted for him in 2016 might not do the same in 2018.
The President, however, is one of the most popular Republican presidents in history among Republicans. Additionally, a significant tax reform bill, rampant deregulation and protectionist policies have meant the economic indicators many people make decisions on, such as unemployment, are positive.