The mid-term elections in the USA will be held tonight, November 3. All 435 seats in the House of Representatives and 35 seats in the Senate are up for election. President Donald Trump said: "If I don't win the midterm elections, I will veto everything." A presidential veto allows the president to veto a bill passed by Congress, preventing it from becoming law. Congress can override a veto with a two-thirds majority in the House and Senate.