To help you keep track of the Tar Heel state's many House races, we've included an interactive map. In North Carolina races where no candidate wins at least 40 percent of the vote, the top two vote-getters will advance to a July 15 runoff. If two candidates each win more than 40 percent, the person with the most votes wins the nomination. In Ohio, a simple plurality is all that's needed.
• NC-Sen (R): Eight Republicans are facing off to take on Democratic Sen. Kay Hagan in November. The Republican establishment has been backing State House Speaker Thom Tillis throughout the race, and their support appears to be paying off at just the right time. For months it looked like Tillis would be forced into a runoff, but recent polls show him winning the nomination outright after a barrage of pro-Tillis ads boosted his name recognition. If the speaker fails to take the 40 percent-plus-one vote he needs, look for physician Greg Brannon or pastor Mark Harris to meet him in the runoff.
Head over the fold for a look at both state's House primaries.
• NC-02 (D): Two Democrats are jockeying to take on Republican Rep. Renee Ellmers in this Republican-leaning seat. Singer and 2003 American Idol runner-up Clay Aiken started out the race far better known than his opponent, former state Commerce Secretary Keith Crisco. However, Crisco quickly went negative and portrayed Aiken as more interested in being a celebrity than a public servant. Thanks in large part to Crisco's personal funds, he has outspent Aiken and stands a good chance at pulling off an upset Tuesday.
• NC-03 (R): Republican Rep. Walter Jones has been an iconoclast in the House GOP caucus for years: Among other things, Jones was one of very few Republicans to back banking reforms and refused to vote for John Boehner in the 2013 speaker race. Former Treasury aide and political consultant Taylor Griffin is presenting himself as a much more pure conservative. Griffin and his well-funded allies have been hitting Jones on the air and may be able to unseat Jones in the primary. However, Griffin has his own vulnerabilities: He only recently moved back to North Carolina after years in Washington, DC, and his establishment connections could prove to be a liability to voters.
• NC-06 (R): Nine Republicans are running to succeed retiring Rep. Howard Coble. Rockingham County District Attorney Phil Berger Jr. looks like the best-known candidate and is likely to bring in the most votes. However, given how crowded this contest is, Berger has a tough task ahead of him if he wants to win without a runoff. Greensboro City Councilman Zack Matheny and banker Bruce VonCannon look like Berger's main rivals, with both spending relatively large sums of money in the last few months.
• NC-07 (R): Democratic Rep. Mike McIntyre's retirement gives Republicans an almost-certain pickup in this 59 percent Romney seat. The main contenders are former state senator and 2012 nominee David Rouzer (who came very close to beating McIntyre that year) and New Hanover County Commissioner Woody White. Rouzer's establishment allies have been running ads late in the race, and that could make all the difference here.
• NC-12 (D): Seven Democrats are competing to succeed former Rep. Mel Watt, who left the House to accept an Obama administration appointment. The contenders are state Reps. Alma Adams and Marcus Brandon; state Sen. Malcolm Graham; former Charlotte-Mecklenberg School Board Chairman George Battle III; former Charlotte City Councilor and 2013 mayoral candidate James Mitchell; attorney Curtis Osborne; and former East Spencer Mayor Rajive Patel. Adams has outraised and outspent the other contenders and is probably the most likely to make it to a runoff: The fact that she is the only woman in the race probably will also help her stand out from the crowd. Note that a special primary for the rest of Watt's term will be held Tuesday as well, but that term will only last from November to January.
• OH-14 (R): Freshman Republican Rep. David Joyce won his seat in 2012 without going through a primary. When now-former Rep. Steve LaTourette dropped out of the race after winning renomination, party leaders gave the nod to Joyce. This time it won't be quite as simple, with state Rep. Matt Lynch challenging Joyce. Lynch has a well-deserved reputation as a hardline conservative and has been running to Joyce's right. However, Lynch got into the race late and has raised very little money. Outside groups have also been running ads for Joyce. If Lynch pulls off a surprise that would be very good news for Democrats: The district only went for Romney 51-48 and Democrats have a credible candidate in businessman Michael Wager. Team Blue's chances would undoubtedly be better against the more hardline and underfunded Lynch than against Joyce.
Other races: Indiana, North Carolina and Ohio will each hold state legislative primaries. Additionally, Texas will have a special election in its 4th Senate district. Four Republicans are running, and a runoff will be held at a later date if no one wins more that 50 percent.