US citizens vote Tuesday on crucial mid-term elections to the United States Congress. Thousands of voters have already cast their ballots, taking advantage of an early voting system. The vote is one of the most closely fought mid-term elections of recent years. Just before the vote for a new congress, polls showed that Republicans had a chance of keeping a small majority in the Senate. Democrats hope to win control of at least one of the Houses of Congress. For the first time in 12 years, they are hoping to recapture at least the 435 member House of Representatives. All 435 seats in the House are up for re-election, while a third of the seats in the Senate, and 36 state governor races will also be decided.