India, Nov. 1 -- With Election Day two days away, the outcome of the November 3 midterms will be decided by a small number of Senate and House contests rather than by the nationwide mood alone. Democrats need a net gain of four seats to take the Senate and three to win the House, and the battle for both chambers is concentrated in a handful of states and districts where polls show narrow margins.

The House is considered likely to shift to Democratic control, according to several forecasting models, while the Senate is far more finely balanced. The contests below are the ones most likely to determine who controls Congress for the final two years of Donald Trump's presidency, and which party sets the agenda on spending, oversight and nomin...