Like the Massachusetts race, there were few undecideds left, except here Republicans were hoping that worked in their favor.

Nebraska: Former Sen. Bob Kerrey (D) vs. Deb Fischer (R)

Open seat -- Sen. Ben Nelson (D) is retiring

Republicans began eyeing two-term Democrat Ben Nelson's seat even before he announced his retirement. With Nelson out, Democrats pinned their hopes on Bob Kerrey, the former governor and two-term senator. Although a well-known figure in Nebraska, Kerrey spent most of his post-Senate career outside of the state, primarily in New York City where he served as president of The New School.

The conservative super PAC American Crossroads began running ads against Kerrey before he even declared his candidacy. The Republican nominee is state Rep. Deb Fischer, who scored a surprising win in a crowded GOP primary. Kerrey has an uphill battle to keep the seat blue; Fischer has been leading with at least 50% in both independent and partisan polls.

Nevada: Sen. Dean Heller (R) vs. Rep. Shelley Berkley (D)

Democrats' strength in Nevada was being put to the test once again in a Senate election. With voter registration numbers on their side, seven-term Democratic Rep. Shelley Berkley hoped to deny Republican Sen. Dean Heller a full Senate term (Heller was appointed to the seat after Republican John Ensign resigned).

A House ethics investigation and a lackluster debate performance kept Berkley below Heller in the most recent polls. Heller's strong fundraising ability also helped him keep the advantage in a state with a heavy Latino population that overwhelmingly votes Democratic. Turnout for the presidential race could have the largest impact on the outcome of this race.

North Dakota: Heidi Heitkamp (D) vs. Rep. Rick Berg (R)

Open seat -- Sen. Kent Conrad (D) is retiring

Former state Attorney General Heidi Heitkamp gave Democrats their best opportunity to keep the seat of retiring five-term Sen. Kent Conrad. Republicans hoped first-term Rep. Rick Berg will repeat the party's success of 2010, when they took over retiring Democrat Byron Dorgan's seat.

The state has a history of split-ticket voting, giving Heitkamp an opportunity to show her independence from national Democrats. She's publicly disagreed with Barack Obama on issues like energy, which she points to as evidence she won't be a rubber stamp. She enjoyed high favorables and solid support from Republican ticket-splitters and has hammered Berg for his connection to a controversial real estate company.

With the lowest unemployment rate in the country, North Dakotans had their choice between two candidates with strong statewide appeal.

Ohio: Sen. Sherrod Brown (D) vs. Josh Mandel (R)

CNN projection: Sen. Sherrod Brown wins

Primarily because of those frequent trips from President Barack Obama and Republican candidate Mitt Romney, the contest between Brown and Mandel played out in Ohio against the backdrop of the presidential election.

Fueled by Super PAC money and advertising, the race got nasty at times. In total, $67 million dollars was spent in the election, according to the Center for Responsive Politics. Much of that - $34 million -- was sent by outside groups advocacy groups.

At the three debate, Mandel and Brown battled over the auto bailout, abortion and each other's record. The testiness of the race spilled out on the debate stage -- at one debate Mandel told Brown to "calm down" and called him "a liar."

Brown was first elected to the Senate in 2006, during a wave of Democratic victories in the Senate and House. Throughout most of the 2012 race, especially in September and October, Brown led Mandel by around 10 percentage points in independent poling.

Pennsylvania: Sen. Bob Casey (D) vs. Tom Smith (R)

CNN projection: Sen. Bob Casey wins

Though recent polls have given Republicans hope where they previously had little, freshman Democratic Sen. Bob Casey of Pennsylvania was re-elected Tuesday.

GOP candidate Tom Smith, a wealthy business executive, lagged far behind Casey for much of the race.

In the last few weeks, he spent heavily on advertising and was able to narrow the polls. But he never took the lead

Virginia: Former Gov. Tim Kaine (D) vs. former Gov./Sen. George Allen (R)