Chance of winning control

Key 50% 60 70 80 90 D R The vice president breaks ties in the Senate. is the probability of a 50-50 split in the Senate with a Democratic vice president. is the probability of a 50-50 split with a Republican vice president.

# How the odds have changed We'll be updating our Senate forecasts every time new data is available, every day through Nov. 8.

# Who’s ahead in each Senate race Our win probabilities come from simulating the election 20,000 times, which produces a distribution of possible outcomes for each race. Here are the expected margins of victory in each state. The closer the dot is to the center line, the tighter the race. And the wider the bar, the less certain the model is about the outcome. Key Average 80% chance outcome falls in this range Show all states ▾

The balance of power in the next Senate In each simulation of the Senate elections, we forecast the winner of all 34 races and note the resulting number of seats that would be held by the parties. That gives us a distribution of possible outcomes.

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What the next Senate might look like More than twice as many Republican seats are up for election this year as Democratic seats, giving Democrats more opportunities to build a majority. To win control of the chamber, they'll need to net four additional seats — if they win the presidency. Without the White House, they'll need five.

# How much each race matters Two measures help capture how important a state and its voters will be in determining which party controls the next Senate: “Tipping-point chance” is the probability that a race will decide whether the Democrats or Republicans are in the majority. “Voter power index” is the relative likelihood that an individual voter in a state will determine the majority party. Tipping-point chance North Carolina 19.1% Missouri 17.0 % New Hampshire 12.9 % Indiana 11.4 % Pennsylvania 10.5 % Nevada 9.9 % Florida 6.2 % Wisconsin 4.1 % Kentucky 2.5 % Georgia 1.2 % Colorado 1.1 % Arizona 1.1 % Illinois 0.5 % Ohio 0.5 % Louisiana 0.5 % Arkansas 0.4 % Alaska 0.3 % Iowa 0.2 % Washington 0.1 % South Carolina <0.1 % Connecticut <0.1 % Maryland <0.1 % Oregon <0.1 % Idaho <0.1 % Kansas <0.1 % Alabama <0.1 % South Dakota <0.1 % Utah <0.1 % Oklahoma <0.1 % Vermont <0.1 % Hawaii <0.1 % New York <0.1 % North Dakota <0.1 % California <0.1 % Voter power index New Hampshire 17.3 Nevada 8.8 Missouri 5.9 Indiana 4.2 North Carolina 4.0 Pennsylvania 1.8 Kentucky 1.4 Wisconsin 1.3 Alaska 1.1 Florida 0.7 Arizona 0.4 Arkansas 0.4 Colorado 0.4 Georgia 0.3 Louisiana 0.2 South Dakota 0.2 Iowa 0.1 North Dakota 0.1 Illinois <0.1 Ohio <0.1 Idaho <0.1 Oklahoma <0.1 Hawaii <0.1 South Carolina <0.1 Vermont <0.1 Washington <0.1 Oregon <0.1 Connecticut <0.1 Alabama <0.1 Kansas <0.1 Maryland <0.1 Utah <0.1 New York <0.1 California <0.1 Show all states ▾

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