Exhaustive polling of 40,000 election simulations showed Senate was expected to be decided by key races in Pennsylvania, Georgia and Nevada
Republicans have a 55 per cent chance of winning control of the Senate, according to an exhaustive final analysis.
The polling site FiveThirtyEight ran 40,000 simulations of the election, based on polls and expert opinion.
A sample of 100 outcomes showed Republicans would win 55 times and Democrats 45 times.
The average number of seats each party would win in the 100-seat chamber was 51 for Republicans and 49 for Democrats, which would give Republicans control.