U.S. Sen. Lindsey Graham's six Republican primary opponents have spent months picking apart his 12-year Senate career.

Too quick to compromise, they say. Too friendly with Democrats in some instances or, in others, too hawkish and too close to Arizona Republican Sen. John McCain.

He's even had nice things to say about former Secretary of State Hillary Clinton, the Democratic front-runner for the White House in 2016, if she gets into the race.

But are these legitimate weaknesses of the state's senior senator? Or are they arguments tossed out by long shots?

With a month to go until the GOP primary, Graham's performance as a senator - sometimes working across the aisle, sometimes in opposition to other Republicans - largely remains the singular issue of the campaign.

The Post and Courier recently asked Graham's six challengers to each cite a factor they say makes him unworthy of another term in Washington.

Graham was given an opportunity to respond, but his campaign declined.

"Sen. Graham has agreed to debate his opponents before the June 10 primary. Until then, he plans to continue focusing his efforts on persuading the more than 400,000 Republicans who will cast their ballots for the next U.S. senator," a spokesman said. That debate is June 7.

Graham called this primary "a referendum on the times in which we live," adding, "What we can't survive without is finding common ground."

Opposing him in the primary are Det Bowers, a Columbia minister; Lee Bright, a state senator from Spartanburg; Upstate businessman Richard Cash; Bill Connor, an Orangeburg attorney; Benjamin Dunn, a Columbia lawyer; and Charleston-area businesswoman Nancy Mace.

Read what these opponents say about his record in the graphic above.