Samuel Wurzelbacher, better known as "Joe the Plumber," became a conservative icon in the 2008 presidential race when he challenged then-candidate Obama on tax policy at a campaign event. Republican John McCain even mentioned him during the third presidential debate. Four years later, Wurzelbacher is running for Congress in a quixotic race against 15-term incumbent Democrat Marcy Kaptur, who is a safe bet for re-election. Kaptur handily defeated fellow Democrat Dennis Kucinich in a primary earlier this year.

Ohio 16: Rep. Jim Renacci (R) vs. Rep. Betty Sutton (D)

Ohio's most competitive House race pits freshman Republican incumbent Jim Renacci against three-term Democratic incumbent Betty Sutton. Since August, the two have benefited from about $2 million in ad spending on their behalf from parties and outside groups, while Renacci's campaign has about doubled Sutton's campaign in ad spending. the merged district, located in northeastern Ohio near, but not including, Cleveland, Akron, and Canton, leans Republican but the race remains up for grabs.

Tennessee 4: Rep. Scott DesJarlais (R) vs. Eric Stewart (D)

Republican physician Scott DesJarlais was elected to Congress in the Republican wave of 2010, defeating Democratic Rep. Lincoln Davis. He was a safe bet for re-election until a recent revelation that he had pressured a girlfriend to have an abortion a decade ago. DesJarlais was separated from his wife at the time. The Democratic nominee is Eric Stewart, a state senator. He has begun making an issue of the incident but the impact on DesJarlais' campaign in this rural, conservative district remains unclear.

Texas 23: Rep. Francisco Canseco (R) vs. Pete Gallego (D)

Republican Francisco "Quico" Canseco is one of many freshman members elected in the GOP wave of 2010 who now finds himself in a competitive race for a second term. Canseco was a wealthy commercial real estate developer when he won his third bid for this seat two years ago, defeating Democratic incumbent Ciro Rodriguez. After a legal battle over the redistricting process, Canseco ended up with a district that is slightly more Democratic -- President Obama carried it in 2008 with 51%, according to the Cook Political Report.The Democratic nominee is Pete Gallego, a state representative who defeated former Rep. Rodriguez in the primary. Hispanics make up 66% of voters.

Utah 4: Rep. Jim Matheson (D) vs. Mia Love (R)

As Utah's only Democratic member of Congress, Jim Matheson is used to close races. He barely squeaked by in 2010 with 50% of the vote. This year may prove to be Matheson's toughest race yet. His Republican opponent is Mia Love, the mayor of Saratoga Springs who would become the first female African-American Republican to serve in Congress. Love is a rising star in the party and was giving a prominent speaking role at this year's Republican National Convention. The two have been relatively evenly matched in fundraising. This is one of the most competitive and highest profile House races in the country.

Wisconsin 1: Rep. Paul Ryan (R) vs. Rob Zerban (D)

Being named Mitt Romney's vice presidential running mate has not affected Paul Ryan's chances at getting re-elected to the House. He is a safe bet for against Kenosha County Supervisor Rob Zerban.

Ryan has been asked multiple times whether he's hedging his bets by running for re-election while also running for vice president but the question is irrelevant. Ryan was tapped for the ticket after the deadline had passed to have his name removed from the House ballot. He's far from the first running mate to run for two jobs at once. Vice President Joe Biden was in the same position in 2008.

Wisconsin 7: Rep. Sean Duffy (R) vs. Pat Kreitlow (D)

Rep. Sean Duffy was one of the higher-profile freshmen elected in the Republican wave of 2010. He was a former Ashland County district attorney and tea party favorite, but he was probably best known for his work as a professional lumberjack athlete and ESPN commentator and as a cast member on MTV's reality show "The Real World." This year he faces a tough challenge from Pat Kreitlow, a former state senator and former local TV news anchor. Redistricting gave Duffy a more-GOP-leaning district. He also enjoys a financial advantage. Despite these advantages, this remains the most competitive House race in Wisconsin.