Which party will win the 2026 U.S. Senate election in New Hampshire?

rationale:

State of the Race Following the September 8 primary, the matchup for New Hampshire's open Senate seat is set between Democratic Rep. Chris Pappas and Republican former Sen. John E. Sununu 2 sources. While minor candidates like the Constitution Party's Edmond Laplante and a few independents are on the ballot, none have a realistic path to victory in a heavily nationalized race, leaving the probability of an "Other" victory at 1% 2 sources.

Polling and Public Opinion The race is highly competitive, though Pappas maintains a modest mid-single-digit lead in most averages. The RealClearPolling average shows Pappas ahead 45.5% to 41.5% realclearpolling.com. However, recent individual polls reveal a volatile electorate. A September 9–11 co/efficient survey found the race tied at 46% battlegrounds.coefficient.org, and an August UNH poll showed Sununu narrowly ahead by two points scholars.unh.edu. Conversely, other recent surveys, such as Rasmussen and Saint Anselm, have Pappas leading by 11 and 7 points, respectively 2 sources. This variance points to genuine tightening, though the modal outcome remains a Pappas lead.

Fundamentals and Campaign Finance Structural factors heavily favor the Democratic nominee. The national environment is strongly Democratic, with generic ballot averages hovering between D+6.6 and D+7.6 natesilver.net. Furthermore, New Hampshire has not elected a Republican to the Senate since 2010 2 sources. Pappas also boasts a significant hard-dollar fundraising advantage, outraising Sununu roughly $15.4M to $4.1M 2 sources. However, Sununu's financial deficit is largely offset by a massive influx of Republican outside money, including a $9.6M television buy by "No Going Back" and substantial early spending from Americans for Prosperity newhampshirebulletin.com.

Overall Assessment While prediction markets have priced a Democratic victory at approximately 83–84% 3 sources and organizations like DDHQ assess Pappas's chances at roughly 77–78% 2 sources, qualitative handicappers are urging caution. Both the Cook Political Report and Inside Elections recently shifted their ratings for the race to "Toss Up," citing the tightening polls, Sununu's strong candidate profile, and overwhelming GOP outside spending 2 sources. Balancing the structural Democratic tailwinds and persistent polling averages against the very real momentum and financial parity backing Sununu, the probability of a Democratic hold sits at 75%. Pappas remains the distinct favorite, but the race is undeniably tighter than the early September market consensus implies.