He's a key negotiator on Capitol Hill, brokering a bipartisan immigration bill, taking a leading role in U.S. foreign policy, and dismissing colleagues who choose gridlock over compromise, but it is no secret that Sen. Lindsey Graham, R-S.C., has problems at home.
"Lindsey is all out there making deals and on CNN and that rankles a lot of people up down here," says David Woodard, a South Carolina GOP strategist and professor of political science at Clemson University. "The natives are restless for the GOP primary."
Pundits say Graham's fractured relationship with the tea party in South Carolina has fostered an undercurrent of dissatisfaction among the base that the right primary challenger could harness and use to beat the two-term senator in a primary.
"He feeds them red meat in South Carolina, but then goes up to Washington and cuts deals with Obama and the Democrats," says Dan Tripp, a GOP campaign strategist in South Carolina. "He has become a status quo senator. We have seen [that] some pretty big incumbents have lost because of that same narrative."
It will all come down to cash. Already, campaign finance reports show Graham has $6.3 million in the bank.
The Graham campaign says it looks forward to a "spirited campaign."
"Lindsey Graham is a strong fiscal, social, and national security conservative with the record to back it up," says Tate Zeigler, a campaign spokesman. "Whether it's repealing and replacing Obamacare, working to ensure the Port of Charleston is deepened, standing up for the unborn, protecting the Second Amendment, or ensuring we have a strong military, Senator Graham works tirelessly for the people of South Carolina."
But three candidates have announced they think Graham works too closely with Washington and isn't conservative enough. They have vowed to bring him down.
Nancy Mace declared her candidacy Saturday. She hasn't sought office before, but no voting record might give her the best shot at going up against Graham, pundits say.
"She is inexperienced, but sometimes not holding office is a plus in South Carolina. Voters see you are not painted by politics and assume you must be OK," says Woodard.
Mace has made headlines in South Carolina before. The daughter of Army Brig. Gen. Emory Mace, she was the first female graduate of The Citadel, a prestigious military college in South Carolina. During her announcement Saturday, Mace said running for office was never part of her plan, but she is jumping in the race because she says "government is out of touch."
"We cannot change Washington unless we change who we send to Washington," Mace said during her announcement.
Lee Bright is the latest Graham challenger. The state senator from Spartanburg has not officially declared his candidacy, but launched his campaign website Wednesday.
"As a South Carolina state senator, Lee Bright has earned the reputation for being the most conservative leader in the legislature," a statement on the website reads. "It is time to take this proven track record to the U.S. Senate so South Carolina can lead the charge against the Washington establishment."
Bright ranked 1st out of all 46 state senators in the Palmetto Liberty PAC's annual conservative scorecard, but pundits say he doesn't have the star power or name recognition out of the gate to be a viable challenger against Graham.
"He has not been a huge leader in Columbia," Tripp says. "He has been somewhat of a backbencher from my estimation."
But Bright attracted national media attention earlier this year when he introduced the "South Carolina Gun Safety Program," a bill to sponsor high school shooting classes to teach students how to operate a gun.
He is also well known for supporting a bill to ban Shariah from South Carolina and was behind a push to establish a separate South Carolina currency as backup in case the Federal Reserve faltered.
Richard Cash was the first candidate to challenge Graham in the primary. Cash entered politics in 2010 when he ran for Congress in the primary against Rep. Jeff Duncan. He lost, but it was close, pundits remember.
"This is the best grass roots guy I have ever seen," says Woodard who worked on Duncan's campaign in 2010. "We couldn't beat him. He had a ground war like I had never seen."
Pundits agree that Cash is popular among conservative evangelical voters and has established himself as a small business owner in the community. He owns a "fleet of neighborhood ice cream trucks" and a used car dealership.
"I am a complete outsider to the political establishment; however, this is not my first involvement in politics," Cash said in a letter on his website. "I know how to run, I know how to fight, and I am ready to go."
Conservative groups like Club for Growth and Americans for Prosperity say they are watching the race closely, but have not endorsed a candidate yet.
Pundits in the state says that Graham may be able to escape a primary bloodbath, but only if the field continues to widen and no one candidate establishes themselves as the leader.
"Graham is hoping for the Sanford effect where 16 people were in the primary race," says Woodard, referring to Republican Rep. Mark Sanford's successful comeback earlier this year. "The more people who are in them, the more it helps the incumbent."