The Democrats' probability of sweeping the 2026 midterm elections has surged to a new high of 46%.

According to Polymarket data, since the outbreak of the Iran war, the probability of the Democratic Party “sweeping” the 2026 midterm elections has increased by 5 percentage points, soaring to a new high of 46%, while the Republican sweep probability is currently only 17%. (Note: U.S. midterm elections do not include the presidential or vice-presidential races, but instead elect Congress and some gubernatorial positions. They are seen as a “referendum” or “barometer” on the current president and their party’s performance—if the president’s approval rating is low, their party often loses seats in the midterms; if the Republicans hold or expand their majority, Trump can more smoothly push through agendas such as tax reform, immigration, and trade in the following two years; if the Democrats gain control of one or both chambers, they can block legislation, initiate investigations, and even influence Trump’s last two years in office).