Explained | Key races to watch as Republicans defend narrow House majority

Washington: Republicans in the US House of Representatives are defending a narrow majority in Tuesday's presidential and congressional elections. Democrats need to flip just four seats to win control of the lower chamber.

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Below are some key races to watch:

New York suburbs

Democrats are aiming to seize back several districts in this deeply Democratic state in their quest to recapture the House majority.

New York's 4th Congressional District voted for Democrat Joe Biden by 5 percentage points in 2020, but sent Republican US Representative Anthony D'Esposito, a former New York City police officer, to Congress in 2022 amid a wave of fear about crime. He will again face off against Laura Gillen, an attorney who lost to him by 3 percentage points in 2022.

New York's 17th District was the scene of one of 2022’s biggest upsets, when Representative Sean Patrick Maloney - head of the Democrats' House campaign arm - lost his own race.

Republican Representative Mike Lawler is now defending the seat he flipped against former Democratic Representative Mondaire Jones, who represented much of the district before lines were redrawn.

In the Hudson Valley, Representative Marc Molinaro, a moderate Republican who has worked to build a reputation of bipartisanship, is defending his seat in the 19th District against Josh Riley, who lost by just 1.6 percentage point in 2022.

Maine - Golden distances himself from fellow Democrats

Although Maine leans Democratic at the presidential level, it has a high number of independent and Republican voters, particularly in rural districts like the 2nd.

Democratic Representative Jared Golden frequently votes against his party in Congress and has not attended Democratic caucus meetings since 2021, moves he hopes will make him more appealing in this Republican-leaning 2nd District. Former NASCAR driver Austin Theriault is running against him in what opinion polls show is a tight race. The seat is a top target for Republicans to flip.

Pennsylvania - Swing districts in a swing state

Pennsylvania is a top target for both parties at every level this election. In the 7th District, Democratic Representative Susan Wild is no stranger to tight races. This is her fourth time defending her swing district seat, eking out a win on thin margins each time. Ryan Mackenzie, a Republican state representative, is attempting to flip the seat.

In the 8th District, Democratic Representative Matt Cartwright is defending his northern Pennsylvania seat - which includes Biden’s hometown of Scranton - where Trump won by 4 percentage points in 2020. Cartwright is facing off against Rob Bresnahan, a local businessman.

Arizona and Nebraska - Democrats aim at Biden district Republicans

Republican Representative David Schweikert is defending his seat in Arizona's 1st District, which Biden won by a narrow margin in 2020. The seat is consistently a top target for Democrats but Schweikert has managed to hang on since 2010. This year, Amish Shah, a doctor and Democratic state lawmaker, will try to unseat him.

First-term Republican Representative Juan Ciscomani is defending his seat against Kirsten Engel - a Democratic former state senator - who lost to him by just 2 percentage points in 2022. Biden won this border district by 0.1 percentage point in 2020.

Republican Representative Don Bacon is fending off a challenge from state lawmaker Tony Vargas in Nebraska's 2nd District, which voted for Biden by almost 7 percentage points in 2020.

California - Republicans on defense in farm-heavy valley

Water access is a top issue in California's Central Valley, where agriculture is a major industry. Democrats are hoping to pick up seats in districts that elected Republican representatives but voted for Biden in 2020.

In the 13th District, Representative John Duarte won the second closest House election in 2022, with just over 500 votes separating him from his Democratic opponent, state lawmaker Adam Gray. The pair are facing off again in November.

In the 22nd district, Republican Representative David Valadao is also facing a rematch with his 2022 Democratic opponent - Rudy Salas, a former state lawmaker.

Washington and Oregon - will voters pick moderates?

Representative Marie Glusenkamp Perez, who represents Washington state's 3rd District, is one of the most conservative Democrats in Congress. She flipped her Republican-held district in 2022, after Republicans nominated Joe Kent, a far-right candidate, over the moderate incumbent.

Kent will be attempting to unseat Glusenkamp Perez this year in this largely rural district in the southwestern corner of the state. Voters chose Republican former President Donald Trump by a narrow margin in 2020, and Glusenkamp Perez won by less than 1 percentage point in 2022.

In 2022 Oregon's 5th District - including suburbs south of Portland to north of Eugene - was a major success for Republicans. Representative Lori Chavez-DeRemer, a Republican state lawmaker, flipped it after Democrats nominated a progressive over a moderate incumbent. This time, state Democrats coalesced behind Janelle Bynum, a former state lawmaker who has beaten Chavez-DeRemer in state races before.