What appeared to be an almost certain Republican takeover of the U.S. Senate a year ago is now in serious doubt as Democrats in red and purple states, along with suddenly safer incumbents in Ohio and Florida, look to hold their thin majority in the upper chamber. Republicans must net four new seats to gain control if Obama wins or three if Romney prevails.
Former governor TIM KAINE (D.) vs. former governor and Senator George Allen (R.)
Two popular men with encyclopedic familiarity with their state face off in the new Old Dominion. The battle to replace retiring Democrat Jim Webb has been as closely fought as it has been expensive, but Kaine's fortunes in state polls have risen of late, along with Obama's.
Senator JOHN TESTER (D.) vs. Congressman Denny Rehberg (R.)
The Democrat was targeted early on as an endangered species--a member of Barack Obama's party in a super-red state. But as the race has gotten nastier, with negative TV ads and barbed rhetoric, Tester has proved to be a survivor who has created enough distance from the Beltway to hold on.
Senator CLAIRE MCCASKILL (D.) vs. Congressman Todd Akin (R.)
Once given up for dead by many Democrats, McCaskill got 2012's biggest political gift when Akin made inexplicable remarks about rape that sent most national Republicans fleeing. Akin declined to step down and has kept the race closer than expected, but McCaskill remains the solid favorite.
Congresswoman TAMMY BALDWIN (D.) vs. former governor Tommy Thompson (R.)
Baldwin's bid to keep the seat now held by retiring Democrat Herb Kohl is infused with history: she would be the nation's first openly gay Senator. Thompson's years away from the campaign trail (and time as a D.C. influence peddler) have equalized a race once regarded as a GOP cinch.
Former state attorney general HEIDI HEITKAMP (D.) vs. Congressman Rick Berg (R.)
Berg should be walking away with the race to replace Democratic Senator Kent Conrad, who defied the state's red tilt with a frank and confiding down-home style. But the well-liked Heitkamp has campaigned hard and well and been buttressed by winning TV spots and some Berg missteps.
Congressman CHRIS MURPHY (D.) vs. businesswoman Linda McMahon (R.)
In the rare race that is moving in the GOP's direction this year, pro-wrestling executive McMahon has done well in her second bid to take a Nutmeg State Senate seat. The fight to replace the retiring Joe Lieberman may come down to McMahon's deep pockets vs. the state's deep blue leanings.
Treasurer RICHARD MOURDOCK (R.) vs. Congressman Joe Donnelly (D.)
In a nightmare for Republicans, a once safe seat held by retiring GOP wise man Richard Lugar is very much in play. The disciplined Donnelly has pulled even or ahead in polls, and Republicans are pouring in cash to try to save Tea Party darling Mourdock.
Senator SCOTT BROWN (R.) vs. Harvard professor Elizabeth Warren (D.)