Voters in four states are set to head to the polls on Tuesday to vote in a slew of primaries that will help determine the makeup of the November ballot as both parties vie to take control of the House next year.

Republicans are turning their focus to a handful of races in Maine and Nevada that will determine their party’s candidate to take on some of the most vulnerable Democratic incumbents in the lower chamber. Meanwhile, some GOP lawmakers are facing primary challenges themselves, including Rep. Nancy Mace (R-SC) in South Carolina, that they must survive if they wish to remain in the lower chamber. North Dakota’s lone House seat is up for grabs as well.

Here are five House races to watch on Tuesday:

Nancy Mace faces primary challenger as part of McCarthy speaker vote revenge tour

Mace is facing a tough primary challenge on Tuesday, making her the first of the eight Republicans who voted to oust former House Speaker Kevin McCarthy to fight for her reelection while the former GOP leader actively works against her.

Mace will compete against Catherine Templeton for the GOP nomination for South Carolina’s 1st Congressional District. The race has garnered widespread attention, with Mace facing opposition from some members of her own party, including McCarthy, who has set out on a revenge tour of sorts against the hard-liners responsible for his ouster.

Mace is among the most vulnerable of McCarthy’s detractors as the other five running for reelection face their primary challengers. McCarthy has criticized Mace heading into the primary election, attacking the incumbent over her voting record and the recent turnover in her office.

Templeton has seized on Mace’s vote to oust McCarthy, using it to accuse the South Carolina Republican of being disloyal to her party.

Voters choose among crowded field to replace Rep. Jeff Duncan

South Carolina voters will also have the opportunity to choose their favored candidate to replace Rep. Jeff Duncan (R-SC), who announced earlier this year he would not run for an eighth term in Congress.

Duncan’s retirement leaves the seat open for the first time in over a decade, attracting a crowded primary field of seven Republican candidates. Whoever wins the primary is favored to win in November, as the district is considered to be reliably Republican. The Cook Political Report rates it as R+21.

Because the field is so big, it’s likely no candidate will receive more than 50% of the vote, which would trigger a runoff election later this year. Among those running for his seat are state Rep. Stewart Jones and local pastor Mark Burns.

North Dakota voters to decide Kelly Armstrong’s successor

Voters in North Dakota will vote in their primary for the state’s only House seat, which is being vacated by Rep. Kelly Armstrong (R-ND), who has instead opted to run for governor.

Armstrong’s retirement from the House has attracted a crowded field of GOP contenders vying for the Republican nomination, including former foreign service officer Alex Balazs, former state Rep. Rick Becker, Public Service Commissioner Julie Fedorchak, former Miss America Cara Mund, and Sharlet Mohr, who previously ran an unsuccessful bid for the Williston Basin School Board in 2023.

Balazs benefits from the endorsement of the state GOP, while Fedorchak has dominated the field in terms of fundraising.

Whoever wins the Republican nomination is favored to win the seat in November, as the district is rated as R+20 by the nonpartisan Cook Political Report. 

Vulnerable incumbent Jared Golden to get his challenger

One of the most competitive elections of the 2024 cycle is the House seat for Maine’s 2nd District, which is held by Rep. Jared Golden (D-ME).

House Republicans view Golden’s seat as one of their best pickup opportunities, as former President Donald Trump won the district in both 2016 and 2020. However, Golden has proved himself to be a strong candidate after defeating Republican Rep. Bruce Poliquin in 2018 and then winning reelection two years later despite Trump’s victory in the district.

But Republicans are hoping they can unseat Golden this year. Among those running are state Rep. Austin Theriault, a former NASCAR driver who has the support of Trump and House Speaker Mike Johnson (R-LA). Trump’s support could boost Theriault in the GOP primary among voters who have backed the former president in the last three presidential elections.

Theriault will face off against state Rep. Michael Soboleski in the GOP primary. Theriault holds a major financial advantage, with the most recent campaign finance records showing he has raised $1.2 million throughout his campaign compared to Soboleski’s $117,000.

The district is rated as R+6.

Republicans will choose challenger for Susie Lee, another vulnerable Democrat

Meanwhile, in Nevada, Republicans will also head to the polls to pick their candidate to challenge incumbent Rep. Susie Lee (D-NV).

The primary has attracted a crowded field of seven candidates seeking to unseat Lee in November in a race that is deemed to be one of the most competitive of the 2024 cycle. The district is rated D+1 by the Cook Political Report. 

Among those running for the GOP nomination is Marty O’Donnell, an independently wealthy candidate who is known for composing music for popular video games such as Halo and Destiny. O’Donnell has received the support of top Republicans in the state, including Gov. Joe Lombardo (R-NV), and has spent massive amounts of money from his own pockets since launching his campaign in March.

Also running for the nomination is former state Treasurer Dan Schwartz, who could benefit from statewide name recognition after running in nearly every election cycle in Nevada since 2012. During that time, he has lost multiple congressional bids and the governor’s race in 2018.

Other candidates include attorney Steve Schiffman, entrepreneur Brian Nadell, former state Sen. Elizabeth Helgelien, tax analyst Drew Johnson, and Steve London.