Five Senate Cliffhangers as Election Nears

Republicans and Democrats battle in races that should have been settled long ago.

Supporters of Republican Senate candidates Richard Mourdock (Indiana) and Todd Akin (Missouri) wave campaign signs.

It is down to the final days before Nov. 6, and the race for who controls the U.S. Senate is arguably as hot as the battle over who will win the White House. There was a time when Republicans seemed likely to take back the Senate, but missteps, big money and good old-fashioned ground games have led to a few surprises that shouldn't have been on Election Day. Here's a roundup of the Election Day nail biters to watch.

North Dakota: A Republican will have to eke out a win.

Democratic candidate for the North Dakota's U.S. Senate seat, Heidi Heitkamp, shakes hands with Republican U.S. Rep. Rick Berg, R-ND following a debate in Bismarck, N.D., on Thursday, Oct. 25, 2012.

Republican Rep. Rick Berg looked like a shoo-in six months ago. He was on track to win retiring Democratic Sen. Kent Conrad's open seat, and no one was talking about Democratic candidate Heidi Heitkamp. No Democratic presidential candidate since President Lyndon Johnson has carried the state and GOP presidential hopeful Mitt Romney has a double digit lead over President Obama there.

But Heitkamp is charming North Dakota. And most pundits agree the state is still anybody's game.

"North Dakota looked like a sure pickup too, and now that is in question," says Kyle Kondik, an expert on congressional races at the University of Virginia.

The North Dakota matchup looks very different than other barn burners around the country. An oil boom in the state has kept unemployment under 4 percent meaning the conversation isn't about the bad economy, but about how to keep the good times going. Both candidates support building the Keystone XL pipeline and would like to see the federal government focus its attention on gaining energy independence by developing oil and wind resources in the state.

"We took a race that no one thought was going to be competitive, and we have made it a real race," Heitkamp said. "We are continuing to do the kind of campaign we think North Dakotans expect and deserve, spending a lot of time crisscrossing every corner of the state, and it is paying off."

A Mason-Dixon poll shows Heitkamp behind by two points, but experts says she's still within reach. And outside money is pouring in from both sides.

Connecticut: Republican Linda McMahon holds strong.

Connecticut Senate candidates Chris Murphy, left, and Linda McMahon, right.

She's outspent her Democratic opponent Rep. Chris Murphy more than four to one, and while she trails in almost every poll, it isn't by much. This is McMahon's second attempt at an open Senate seat and she's certainly running much closer than she was two years ago. Murphy has been plagued by Republican claims that he mismanaged his personal finances and the race has gotten a little too close for comfort for Democratic pundits in the state. McMahon, who managed World Wrestling Entertainment and has never held state-wide elected office, has outsider appeal while Murphy is part of the unpopular House of Representatives.

Wisconsin: "Tommy" could lose the $50 million race.

Republican candidate for Wisconsin's U.S. Senate seat, former Gov. Tommy Thompson, left, participates in a debate against Democratic candidate U.S. Rep. Tammy Baldwin at Marquette University Friday, Oct. 26, 2012, in Milwaukee.

It's the $50 million race. It is so close that polls swingback and forth by the week. Democrat Rep. Tammy Baldwin got a big post-convention bump in the Badger State. But former Gov. Tommy Thompson is gaining popularity among independents in the swing state. In 2008, Obama won Wisconsin by 14 points. In 2010, the tides turned and Republicans swept the state house and the gubernatorial race. And Republicans again came out to support Gov. Scott Walker in his recall election earlier this year. This time around, the Senate race has been a showdown of which candidate can make the other one seem more extreme. Thompson and his allies have found some success linking Baldwin to Obama. "With Tammy Baldwin that far left of Obama and Pelosi, she's way too extreme for Wisconsin," says one ad by Karl Rove's Crossroads GPS. And Baldwin has been able to turn Thompson's time as a D.C. consultant against him. One union ad against Thompson claims "he's fighting to give [big oil and huge corporations] tax breaks while he sticks Wisconsin families with the bill. If Thompson is fighting for them, he won't be fighting for us."

And if the closeness of the race isn't enough to keep you guessing, the race is a historic one. If she wins, Baldwin would be the first openly gay member of the U.S. Senate.