Battle to Congress will, like White House contest, be close, decided by handful of states, districts

The contest between Democrats and Republicans to control Congress heads into Election Day much like the presidential race – very close with the outcomes boiling down to just a few states and congressional districts. 

Democrats going into Tuesday control the 100-seat Senate with a 51-49 majority, of 47 Democratic senators and four independent senators – Bernie Sanders of Vermont, Angus King of Maine, Kyrsten Sinema of Arizona and Joe Manchin of West Virginia, all of whom typically vote with the majority party. 

If GOP presidential nominee former President Donald Trump wins, Republicans need to flip just one seat to gain control of the Senate because the vice president serves as the tie-breaking vote in the chamber. If Vice President Kamala Harris wins, Democrats can afford to lose one Senate seat.

The GOP's best chance of flipping a Senate seat is in deep-red West Virginia, where outgoing Republican Gov. Jim Justice leads his Democratic challenger by 34 points, according to one of the most recent polls. The seat is held by Manchin, who was a Democrat until becoming an independent earlier this year. 

Republicans' next likely pickup could come in Montana, where incumbent Democratic Sen. Jon Tester is trailing GOP challenger Tim Sheehy by about 6 percentage points, according to the latest polling average from RealClearPolling. Tester has served in the Senate since 2006.

Other possible pickups for Republicans include Ohio, where Democratic Sen. Sherrod Brown is statistically tied with GOP challenger Bernie Moreno; Wisconsin, where Democratic Sen. Tammy Baldwin is fighting off a tough challenge from Republican Eric Hovde; and Pennsylvania, where Democratic Sen. Bob Casey's early lead has dwindled to a near deadlock against Republican David McCormick.

One other GOP target is the open Michigan Senate race, but Democratic Rep. Elissa Slotkin is leading former Rep. Mike Rogers by 2.4 percentage points, according to RealClearPolling's latest average.

A wildcard in the battle to control the chamber is the race in Nebraska, in which Republican incumbent Sen. Deb Fischer is facing a tough challenge in independent candidate Dan Osborn. 

Republican control the 435-seat House, but also by a narrow margin – 220 seats to Democrats' 212, with three vacancies. All 435 seats are up for grabs Tuesday, and the party holding the gavel in January will likely be decided by less than 20 competitive races.

There are seven swing districts in New York that could determine control of the chamber. Five of those districts are currently held by first-term Republicans, including Long Island districts one and four, Hudson Valley districts 17, and 19 as well as the 22nd congressional district in Syracuse. Districts three and 18 are represented by Democrats.

There are six competitive races in California that will influence which party wins the majority, in districts 13, 22, 27, 41, 45 and 47.

Other races to watch include the contest between Rep. Don Bacon, R-Neb., who is running for reelection against state Senator Tony Vargas as well as Alabama’s second district race between Democrat Shomari Figures and Republican Caroleene Dobson, both lawyers.

Rep. Don Davis, D-N.C., who represents the first congressional district in the state, is fighting to hold his seat against Republican Laurie Buckhout, in a closely-watched tight race.