When the US goes to the polls on 8 November, it won’t just be a test for those politicians seeking re-election, but also of President Joe Biden’s popularity.

The midterms take place every two years in the middle of a four-year presidential term. They include elections for all 435 seats in the House of Representatives and around a third of the US Senate (35 seats). There will also be contests in 36 states for governorships.

To have any real impact over the next 24 months, the White House needs the Democrats to keep control of the Senate. It is currently split 50/50, with Democratic vice president Kamala Harris casting a vote when the ballot is tied.

Retaining the Senate would mean Biden could appoint his chosen candidate to the US Supreme Court should a vacancy arise. These must be nominated by the President and then confirmed by the Senate.

The Senate also has the authority to ratify international agreements that do not relate to foreign trade. This could be significant if there is agreement on a new multilateral climate change treaty at next month’s UN conference in Egypt.

There is also the spectre of former president Donald Trump. These are the first national elections since 6 January 2021 when thousands of his supporters violently stormed the US Capitol building and many pro-Trump candidates are standing in the midterms.

Presidential parties tend to suffer defeats in midterms. Bill Clinton in 1994 and George W Bush in 2006 lost control of Congress (both the Senate and House of Representatives). To pass legislation at the federal level, bills must progress through both houses. This will become virtually impossible if, as expected, the House of Representatives switches to the Republicans.

Democrat hopes

Despite Biden’s current low approval figures and pessimism about the economy, Democrats believe they may have some momentum heading into November. Petrol prices are well below their summer highs and the employment rate is ticking upwards. This has helped ease fears about a potential recession, although concern is rising again.

Polling from September demonstrated why Democrats are hopeful they can win a majority in the Senate. In Arizona and Pennsylvania, the Democrat candidates led their Republican opponents by four percentage points, in North Carolina and Ohio Democrats were neck and neck, while Georgia remains incredibly close.

During October, Republicans saw polls turning back in their direction. The Senate race in Nevada, for example, which was an unexpected toss-up in September, is now moving toward the Republicans, according to recent polling.

President Biden secured major legislative victories last year, including on infrastructure investment, climate change and gun control.

The results of the midterms will not only determine the future legislative scope of Joe Biden’s presidency, but potentially whether he will be able to seek re-election in 2024. A poor election night is likely to renew calls for Biden not to run again. Former president Obama is joining the Democratic campaign trail ahead of the midterms.

What issues count?

The Supreme Court’s decision to overturn Roe v Wade (the constitutional ruling that gave women access to an abortion) in June 2022 has proved to be a key factor in the campaigns. Research from the NGO Kaiser Family Foundation has shown that in the aftermath of this, a majority (59%) of women voters aged 18 to 49 are now more motivated to vote and that there’s been a surge in women registering to vote.

This could be significant in November. In the 2020 presidential election, women made up 52% of the electorate.

Across the US there are Republican candidates for governor, state attorney general and other roles who do not recognise Joe Biden as the duly elected president. Around 291 Republican nominees on the ballot for House, Senate and key statewide offices have denied or questioned the outcome of the last presidential election, according to a Washington Post analysis. If they win, these representatives will have massive powers over state-wide elections and could choose to reject election results in their state in 2024.

Return of Trump

The outcome of the midterms could set the stage for Donald Trump to announce a possible second run for the White House. Trump has campaigned to oust Republicans that voted to impeach him in February 2021 and loudly backed candidates he approves of. So far, 91% of his endorsements have won their open primary election contests.

A recent PBS NewsHour/NPR/Marist poll found that almost 70% of Republicans would support Trump. However, only 28% of independent voters would back him in 2024 and more than 60% of Americans in general are against a second Trump White House bid.

In the 2018 midterms, Trump became a toxic figure for moderate, college-educated, mainly female voters. This key voting bloc may be important again in 2022.

Gary Jacobson, professor emeritus of political science at the University of California at San Diego, has argued that Trump’s post-2020 election schemes and “their baneful consequences” have the potential to affect the standing of the Republican Party for years to come.

The last few weeks of campaigning will be crucial. On 17 October, a national YouGov poll for CBS News had Republicans ahead on 47%, with the Democrats on 45%. The Democrats have one big card left to play in the final stretch: Barack Obama.

The former president remains a popular figure among the party faithful, can still draw massive crowds and will energise campaign workers. Obama has agreed to travel to the key states of Georgia, Michigan and Wisconsin later this month. All have a mix of competitive Senate, House and governor races.

Over the last few months momentum has swung back and forth between Republicans and Democrats, making these midterms unusually unpredictable. The outcome will undoubtedly impact the lives of millions of Americans, as well as influencing whether fair elections will be held and counted in a politically hostile and bitterly divided America.

This article is republished from The Conversation under a Creative Commons license. Read the original article.