On the Senate side, Democrats currently hold a 53-47 advantage, including independents who caucus with them. The outcomes of these races will determine in large measure whether that advantage grows, stays the same or evaporates. Similarly, in the House, where Republicans now have a 240-193 advantage, the races below are important in shaping the House in the next Congress.
SENATE
Connecticut: Self-financed wrestling impresario Linda McMahon challenges Democratic Rep. Chris Murphy to fill the seat of retiring Josph Lieberman.
McMahon (R)
Murphy (D)
Missouri: Democratic incumbent Claire McCaskill faces Rep. Todd Akin in a race consumed by controversy over Akin’s remarks on “legitimate rape” and pregnancy.
Akin (R)
McCaskill (D)
Massachusetts: Incumbent Republican Scott Brown faces challenger Elizabeth Warren for seat long held by Ted Kennedy.
Brown (R)
Warren (D)
Indiana: Tea-party backed Robert Mourdock knocked off incumbent Richard Lugar in the primary. Now, his own rape comments have put him on the defensive vs. Democrat Joe Donnelly.
Mourdock (R) 44%
Donnelly (D) 50%
Est. 24% reporting
Montana: Democratic incumbent Jon Tester faces an uphill battle against Rep. Denny Rehberg in a state where President Obama is deeply unpopular.
Rehberg (R)
Tester (D)
Wisconsin: Republican former governor Tommy Thompson and Tammy Baldwin, bidding to become the country’s first openly gay senator, have been locked in a close race.
Thompson (R)
Baldwin (D)
Virginia: Two former governors — Republican George Allen and Democrat Tim Kaine — are battling for the seat currently held by Democrat Jim Webb, who did not run for reelection.
Allen (R) 51%
Kaine (D) 49%
Est. 10% reporting
North Dakota: Republican Rep. Rick Berg was heavily favored to beat Democrat Heidi Heitkamp to replace retiring Kent Conrad, but Heitkamp has run an excellent campaign.
Berg (R)
Heitkamp (D)
Arizona: Jeff Flake is favored to hold the seat for the GOP after the retirement of Jon Kyl. But former U.S. Surgeon Generl Rich Carmona has been a scrappy opponent.
Flake (R)
Carmona (D)
Nevada: In a state that’s breaking late for Obama, Democrat Shelley Berkley is hoping to ride Obama coattails against favored Republican Sen. Dean Heller.
Heller (R)
Berkley (D)
Nebraska: A late rush by familiar face Bob Kerrey against prohibitive favorite Deb Fischer in deep-red Cornhusker country. Will it be enough?
Fischer (R)
Kerrey (D)
HOUSE
Texas, 23rd District: It’s a squeaker between Tea Party stalwart and incumbent Francisco “Quico” Canseco and Alpine state legislator Pete Gallego.
Canseco (R)
Gallego (D)
Pennsylvania, 12th District: Incumbent Democrat Mark Critz faces a tough challenge from Republican Keith Rothfus.
Rothfus (R)
Critz (D)
Oklahoma, Second District: Ex-DA Rob Wallace is Democrats’ best hope to elect a “Blue Dog,” but that’s not saying much. Markwayne Mullin is favored in super-conservative district.
Mullin (R)
Wallace (D)
Utah, Fourth District: Nowhere will Mitt Romney’s coattails be longer than in Utah, where he might win by 40 points. Mia Love is poised to make history as an African-American congresswoman from Utah.
Love (R)
Matheson (D)
Iowa, Fourth District: Former Iowa First Lady Christie Vilsack takes on Tea-Party firebrand Steve King in very tight race.
King (R)
Vilsack (D)
Minnesota, Sixth District: Michele Bachmann, who briefly held the national spotlight in presidential run, has had a surprisingly tough time putting away challenger Jim Graves.
Bachmann (R)
Graves (D)
Minnesota, Eighth District: Former Rep. Rick Nolan tries a comeback against Tea Party surprise ’10 winner Chip Cravaack.
Cravaack (R)
Nolan (D)
Florida, 18th District: Allen West, one of the most outspoken of the 2010 crop of Republican freshmen, is leading Democrat Patrick Murphy in pre-election polls, but not by much.
West (R) 44%
Murphy (D) 56%
One county reporting
Illinois, Eight District: Tea Party star Joe Walsh is in trouble against Iraq war hero Tammy Duckworth.
Walsh (R)
Duckworth (D)
New York, 19th District: A new, sprawling district is a challenge to hold for Republican Rep. Chris Gibson against Democrat Julian Schreibman.
Gibson (R)
Schreibman (D)
New York, 21st District: Democratic Rep. Bill Owens is in a tight rematch against Republican Matt Doheny in a redrawn district.
Doheny (R)
Owens (D)
New York, 27th District: Republican Chris Collins and Democrat Kathy Hochul are in a bitterly contested, whisker-close race.
Collins (R)
Hochul (D)
California, 15th District: 81-year-old Pete Stark is facing young fellow Democrat Eric Swalwell in a test of what California’s new Top 2 primary system will mean for long-term incumbents.
Stark (D)
Swalwell (D)
California, 26th District: Republican Tony Strickland and Democrat Julia Brownley face off in a newly redrawn district to replace retiring Republican Elton Gallegly.
Strickland (R)
Brownley (D)
California, 52nd District: Republican Rep. Brian Bilbray faces stiff competition from Democratic challenger Scott Peters.
Bilbray (R)
Peters (D)