The 13 Races That Will Determine Senate Majority

President Trump campaigned with Sen. Martha McSally, R-Ariz., in Prescott, Ariz., this month. McSally is a top target of Senate Democrats, who are hoping to flip her seat blue on Election Day.

Republicans hold the Senate 53-47. (There are two independents — Angus King of Maine and Bernie Sanders of Vermont — but they caucus with Democrats and therefore should be counted that way in the math for Senate control.) To flip the Senate, Democrats would need to net-gain four seats outright or three seats and control of the White House, because in a 50-50 Senate — which is possible this year — the vice president breaks the tie. Republicans can lose up to three seats and hold the majority, as long as President Trump wins reelection.

Democrats are forecast to gain two to six seats. Control of the Senate remains a jump ball days out from Election Day. These are the races that will decide it:

Democratic-held seats (Republicans favored to gain one seat)