Resolution criteria

The market resolves based on which party controls the U.S. Senate following elections scheduled for November 3, 2026, when 35 of the 100 Senate seats will be contested. Control is determined by which party holds a majority of seats (51 or more). The Senate currently has 53 Republicans and 47 Democrats (including two independents who caucus with Democrats). Democrats need a net gain of four seats to win a majority, while Republicans can lose no more than two seats to retain control. Resolution will be based on official election results certified by state authorities and reported by major news outlets (AP, Reuters, etc.).

Background

Republicans are heavily favored to retain their Senate majority, as only two Republican-held seats are considered competitive by most rating groups, and Democrats need to flip a minimum of four seats to win a majority. Democrats are defending two seats in states won by Donald Trump in 2024: Michigan, where incumbent Gary Peters is not running for reelection, and Georgia, where the incumbent is Jon Ossoff. Five incumbent Democratic senators represent states won by Kamala Harris by single-digit margins in 2024: New Hampshire's Jeanne Shaheen, Minnesota's Tina Smith, Virginia's Mark Warner, New Jersey's Cory Booker, and New Mexico's Ben Ray Luján.

Considerations

By mid-2025, with Democrats landing their preferred recruits for potentially competitive races and the national environment changing, it was reported that the Senate map was looking better for Democrats. In the Senate, the presidential party penalty is less pronounced than in the House—in 7 of the 20 postwar midterms, the president's party either played to a draw or actually netted seats.