ABC's Shushannah Walshe and Caleb Jackson report:
WHO'S ON THE BALLOT? Today's marquee race is a primary that was supposed to be a much tougher establishment vs. tea party brawl for a senator hated by the more conservative wing of the GOP, but whether he wins without a runoff is what we will be watching for. There is also a challenger hoping to knock down a leader in Virginia, and although there aren't as many choices or potential surprises as last week, there are still plenty of races to watch, including a candidate backed by Oprah Winfrey.
Here are five races to watch this primary Tuesday:
TEA PARTY BRAWL TURNS INTO MORE OF A SNOOZE: Incumbent Sen. Lindsey Graham, who is seeking a third term, will be facing six competitors in today's South Carolina GOP Senate primary. Despite being opposed by tea party groups, he is expected to cruise to victory today against Columbia pastor Det Bowers, State Senator Lee Bright, businessman Richard Cash, attorney Bill Connor, attorney Benjamin Dunn, and businesswoman Nancy Mace, who also happens to be the first female graduate of the Citadel. WHY IT MATTERS: Unlike in Mississippi, where an establishment Republican has a difficult primary, none of Graham's challengers were able to coalesce the anti-Graham vote. Graham has also swamped his opponents in fundraising, raking in cash early in case he did have a more vigorous opponent. The reason to watch tonight is while none of Graham's opponents are expected to win the majority of votes in the primary, the fact that there are six of them could make it difficult for him to receive the 50 percent needed to move on to the general election. If not, he will be forced into a runoff election with the candidate who receives the second-greatest percentage of votes. Even if that does happen it will be in two weeks, making it difficult for one opponent to quickly make their case against Graham.
CANTOR JABBED FROM THE RIGHT: House Majority Leader Eric Cantor is in a primary fight in Virginia's seventh congressional district and he is expected to win easily, but not without getting a little dinged. His opponent, Dave Brat, is an economics and ethics professor at Randolph-Macon College in Ashland, Va., and is running from Cantor's right. The conservative Republican also served under two governors on the Joint Advisory Board of Economists in the state, including under Democratic Gov. Tim Kaine. WHY IT MATTERS: Brat is in favor of tighter border security and has attacked Cantor repeatedly on the issue of immigration. It's definitely a long shot, but he does have some big-name conservative backing: Ann Coulter and Laura Ingraham have both endorsed Brat. In an interview with ABC News last month, Brat said Cantor has lost touch with his constituents, "veering from the Republican creed. Years ago he had a good conservative track record, but now he's veered off. He's not following what folks in his district want him to do and it's hurting the country."
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MAINE'S SECOND CONGRESSIONAL DISTRICT: In Maine, Democratic Rep. Michael H. Michaud is running for governor and there are primaries today on both sides of the aisle. Emily Cain and Troy Jackson, both state senators, are facing off in the Democratic primary election. Cain, backed by Emily's List, is currently the frontrunner, having outraised Jackson by a large margin. In the GOP primary, former Maine State Treasurer Bruce Poliquin is facing former State Senator Kevin Raye. Raye is considered the frontrunner and is the more moderate candidate, which Poliquin has been hitting Raye on. The district, in the northern part of the state, voted for Obama with 53 percent of the vote in 2012.
VIRGINIA'S EIGHTH CONGRESSIONAL DISTRICT: A batch of newcomers - Don Beyer, Lavern Chatman, Adam Ebbin, William Euille, Partick Hope, Derek Hyra, and Mark Levine - are in a crowded Democratic primary to represent a section of Northern Virginia including the Washington, D.C., suburbs of Alexandria and Arlington. Democratic Rep. Jim Moran is retiring, leaving this race wide open. Don Beyer, currently the frontrunner, has served as both the lieutenant governor of Virginia and ambassador to Switzerland under the Obama administration. Beyer has received the endorsement of a few Obama advisers, including David Axelrod. Chatman, who has received the endorsement of Oprah Winfrey, formerly served as the president of the Northern Virginia Urban League. Mark Levine is a radio talk show host and former chief legislative counsel to retired Rep. Barney Frank. Adam Ebbin has served as a Virginia state senator since 2012 and is the first openly gay member of the Virginia General Assembly. Patrick Hope also serves in the Virginia General Assembly, representing Virginia's 47th state district in the House of Delegates. William Euille has served as the mayor of Alexandria since 2003. Derek Hyra is an associate professor of Urban Affairs and Planning at Virginia Tech. Most of the candidates describe themselves as liberal or progressive and it's likely the winner today will be the victor in November.
NEVADA'S FOURTH DISTRICT GOP PRIMARY: The most competitive congressional primary election in Nevada is in the Fourth District. State Assemblyman Crescent Hardy will be taking on African American tea-party candidate Niger Innis in the GOP primary. The winner of this primary will go on to run against Democratic incumbent Rep. Steven Horsford. While Nevada's top two Republicans, Gov. Brian Sandoval and U.S. Sen. Dean Heller, have backed Hardy, the state's Republican Party endorsed Innis, who is the son of Roy Innis, leader of CORE or Congress for Racial Equality, the historic civil rights group. Innis is a nationally recognized conservative, but only moved to Nevada in 2007.
ABC News' John Parkinson contributed to this report.