The votes on 6 November will give US voters their first chance to pass judgment on Donald Trump since he took the White House. Here’s what you need to know about what’s at stake
The key question in these elections is: will Republicans will be able to keep control of both chambers of Congress? Just 35 of the 100 seats in the Senate, and all of the 435 seats in the lower House of Representatives are up for grabs. To take control of the legislative agenda and block Trump's ability to implement his programs, the Democratic party needs to control both houses. With a Senate majority, the Democrats would be able to block cabinet and supreme court appointments. But while they may be able to take the House, clinching the Senate will be much harder. Impeachment, by the way, requires a two-thirds majority in the Senate, so would require Republican votes even if the Democrats won every available seat in November.
Here comes the math: the Grand Old Party (GOP) does have a big advantage over the Democrats in this showdown, because the Democratic party is defending 26 seats (including two independents, who usually vote with them) while the Republicans only have to defend nine.
California has approximately 68 times the population of Wyoming ...
The Senate electoral system is also weighed against the Democrats. Each state gets two senators, irrespective of population, so Wyoming has as many as California, despite the latter having more than 60 times the population. The smaller states also tend to be the more rural, and rural areas traditionally favor the Republicans. One hopeful note for the Democrats is that Nevada and Arizona are both open races – in which the incumbent senator is not running – and both were only narrowly won by the Republicans in 2012.
Democrat
Republican
Independent
Not electing this year
* Minnesota and Mississippi also hold special elections on 6 November. In these states, two seats are in playKey race – Arizona
The Senate seat held by Barry Goldwater and John McCain could be picked up by Democrats in 2018. After a tough primary, Republican Martha McSally has been pushed to the right and faces a tough race against Democrat Kyrsten Sinema in a state with a growing Latino population and with deep tensions between traditional business oriented Republicans like McCain and hard right Trumpists.
218 needed for a majority
The Democrats have a much better chance of winning here. Representation in the House is (relatively) proportional to population, and the whole chamber is re-elected every two years. They need a net gain of 24 seats to win a majority. But in the last 50 years they've scored a net gain of that size only twice, in 1974 and in 2006. In the same period the Republicans have made a 24+ net gain only three times, but the most recent was in 2010, in the midterm elections of Barack Obama's first term.
American voters are usually reluctant to eject a sitting representative. So for Democrats, some of their best hopes are in seats where the incumbent is not standing again. The good news for Dems is that a record 39 Republicans – many of whom were anti-Trump – have chosen to bow out instead of contest their seats in November, and some of those are in key swing states such as Florida and Pennsylvania.
Key race – Pennsylvania's 17th district
Democrat Conor Lamb won a shock special election win in March. Now, after court ordered redistricting, he'll face off against Republican incumbent Keith Rothfus in a far more friendly district. However, it's still a district Trump narrowly won. More key races
Each US state has a governor, who is like a local president. Their interactions with the federal government can be significant; they may have a large amount of sway, for instance, over local gun laws or the implementation of health insurance policies. But this year, Democrats think their salience is national because many of them have a veto over redistricting. Remapping of electoral districts happens in the US after every census. The next round will happen in 2022 when the 2020 census results are in. Governors elected this year who serve four-year terms will still be in office then. Democrats are hoping to win office in several swing states that have open races, such as Ohio, Nevada, Michigan and Florida, and thereby prevent gerrymandering that would affect congressional races as far away as to 2032.
Democrat, open
Democrat, incumbent standing again
Republican, open
Republican, incumbent standing
Not electing this year
Key race – Florida
African American Democrat Andrew Gillum won an upset victory in the primary, bolstered by heavy financial support from Tom Steyer, a billionaire hedge-fund manager. The unabashed progressive will face off against Republican Ron DeSantis, an ardent Trump supporter, in what will be one of the marquee races of the midterms.
US Senate, US House of Representatives, MIT, Brookings Institute, National Conference of State Legislatures, Federal Electoral Commission, National Governors Association