US midterm election: How it works, why it's important and races to watch

US voters head to the polls on November 3, 2026, to elect a new Congress in midterm elections that will serve as a referendum on Donald Trump's second term as president. All 435 House seats and roughly one-third of the 100 Senate seats are up for grabs, with Republicans defending their congressional majorities. The outcome will determine whether Trump's legislative agenda can advance or faces gridlock during his final two years in office. Control of Congress also shapes spending, tax and regulatory policy, making the results a key input for markets and business planning. Watch the House and Senate seat tallies on election night, with divided government a possible outcome if either chamber flips.