(The Center Square) - Labor Day weekend marks the beginning of the final sprint toward the 2026 midterm elections, but one U.S. Senate primary matchup is yet to be determined that could influence the balance of power in the upper chamber.

New Hampshire voters will head to the polls on Tuesday to select partisan candidates for U.S. Senate in a seat without Democratic Sen. Jeanne Shaheen, who is not running for reelection. Her open seat brought a slew of candidates from both parties into the New Hampshire race.

Here is a look at the candidates running in the race.

Among Democrats, U.S. Rep. Chris Pappas, D-N.H., has emerged as a favorite to succeed Shaheen. Pappas first assumed office in 2019 and has focused his campaign on lowering energy costs, and providing more affordable healthcare, housing affordability and grocery costs.

Pappas worked alongside U.S. Sen. Mark Kelly, D-Ariz., to push legislation that would suspend the federal gas tax as prices rose with the U.S. conflict in Iran. He also called for supporting clean energy tax credits, utility assistance for veterans, and protecting the Low Income Home Energy Assistance Program.

Pappas advocated for reducing healthcare costs by capping pharmaceutical drug prices and reversing cuts to Medicaid made through the “One Big Beautiful Bill.”

“He’s pushing to strengthen the Affordable Care Act by making tax credits permanent, and he’s standing up to Republican efforts to cut funding for Medicare and Medicaid,” Pappas’ website reads.

Pappas also said he would push for expanding a child tax credit, and support first-time homebuyers throughout the state.

The congressman is facing a challenge from Karishma Manzur, a scientist, who is also seeking the Democratic nomination for U.S. Senate. Manzur has touted herself as a progressive Democratic candidate in comparison to Pappas.

She has focused on expanding Medicare for All, banning corporate political donations and rent controls for housing in the Granite State. Manzur also called for an immediate pause on the construction of new AI data centers in New Hampshire.

“We need an immediate pause of artificial intelligence technology and the building of hyperscale AI data centers,” Manzur said. “Powerful corporations are lobbying Congress for their benefit, not the benefit of the American people.”

Republicans are also vying to flip New Hampshire’s senate seat in November. Former U.S. Rep. John Sununu has a considerable lead in polling for the GOP ticket while former Sen. Scott Brown trails far behind.

Sununu and Brown lost against Shaheen in 2008 and 2014, respectively. Sununu, whose brother Chris is the former governor of New Hampshire, has focused his campaign on keeping distance from President Donald Trump, despite his February endorsement, and touting his record as a familiar face in the state’s politics.

He called for ending tariffs on building materials to increase affordable housing and investing in tax credits, supporting efforts to pursue fraud in federal benefit programs, and curbing the president’s executive authority.

“Congress needs to step up, review those powers that they've given to the executive and in a bipartisan way, take back the power that was granted to Congress in the first place,” Sununu said in an interview.

Brown has touted his connection to the president despite his lack of an endorsement. The former senator from Massachusetts also served as the United States Ambassador to New Zealand and Samoa during the first Trump administration.

He has focused on supporting the Trump administration’s border policies, lowering grocery costs and fighting against the rising national debt. Brown said he would introduce legislation for a 10% spending cut across all federal agencies to reduce the debt.

“You can’t tell me that every agency can’t find 10% to save,” Brown said. “Every federal department should be audited.”

Pappas holds an enormous lead in campaign fundraising with more than $15 million in contributions and $4.2 million in cash on hand, according to the Federal Election Commission. Sununu follows behind with $4.1 million in contributions and $3 million cash on hand.

Brown follows with $2.1 million in contributions and $416,000 cash on hand. He is followed by Manzur, with $415,000 in contributions and $103,000 cash on hand.

Pappas has received more than $1.4 million through ActBlue, an online campaign fundraising platform for Democratic candidates that has come under fire over fraud allegations. Sununu received $5,000 from the Boston Scientific Corporation PAC and $7,000 from Michael O’Reilly, a consultant and former commissioner of the Federal Communication Commission.

Brown received $6,200 from Lloyd Gainsboro, an executive at Dedham Health and Athletic. Manzur received more than $144,000 from ActBlue.

Polls availability varies by municipality in New Hampshire. However, polls are required to be open by 11 a.m. and cannot close before 7 p.m. on Sept. 8. For more information, visit the New Hampshire Secretary of State, at sos.nh.gov. For early results on Election Day, visit thecentersquare.com/newhampshire.