A new Clemson University poll shows U.S. Sen. Lindsey Graham is having trouble with his Republican base here at home.

Clemson political science professor Dave Woodard conducted the poll last week and found only 31 percent of South Carolina's Republicans plan to vote to re-elect Graham, regardless of who else was in the race.

“This is the lowest 're-elect regardless' figure I have seen for any incumbent in 20-odd years of polling except for one other lower figure,” he said, adding that timing might have played a role.

The poll was taken one week after Graham and U.S. Sen. John McCain strongly supported a United States missile attack in Syria — a decision that 84 percent of the GOP base disagreed with, Woodard said.

Graham's popularity was not as strong as South Carolina's two other high-profile Republicans up for re-election next year: U.S. Tim Scott and Gov. Nikki Haley.

The poll measured the mood of about 500 Republican voters who participated in two of the past three GOP primaries. While 53 percent of them had a favorable opinion of Graham, 36 percent found him unfavorable.

In comparison, 69 percent found Scott favorable and only 6 percent found him unfavorable. Twenty-five percent were undecided.

Haley had a 70 percent favorable response, with 18 percent unfavorable and 12 percent undecided.

Richard Quinn, a Columbia-based consultant to Graham, said he did two recent polls that showed Graham with stronger numbers — numbers equal to Haley's.

Quinn also noted that Woodard had a similarly poor poll result for Graham before his primary six years ago, a primary that Graham ended up winning with 67 percent. He said Woodard's polling has a history of inaccuracies, adding, “I can't explain why because I can't say what his methodology is.”

Woodard noted that Republican primaries often draw about 20 percent of the state's registered voters, “and they are more conservative and more ideological than voters in the general election. It often happens that popular incumbents are derailed on the way to re-election by upstart challengers in GOP primaries.”

The Republican primaries are less than a year away, and Graham already has three GOP challengers: state Sen. Lee Bright, Piedmont businessman Richard Cash and Nancy Mace, a businesswoman who was The Citadel's first female graduate.

Mace said Graham's 31 percent re-elect number shows how dissatisfied voters are with him. “It is clear South Carolina voters are looking for new leadership,” she said. “Sen. Graham has amassed a $6.3 million war chest by serving special interests. However, this poll shows it will take more than money to win a republican primary in South Carolina.”

Neither Haley nor Scott have Republican opponents so far; filing for the offices doesn't begin until March 2014.

Results also showed strong recognition of elected representatives — 99 percent of respondents knew Graham, and 97 percent knew Haley, while 74 percent knew of Scott, who took office earlier this year after Sen. Jim DeMint's resignation.

The poll also asked about voters' likelihood of re-electing the incumbent — regardless of their opponent. It found that Scott has a stronger base of allegiance than Graham, while Haley also is fairly well-liked by voters.

About 45 percent said they would re-elect Haley regardless, while 39 percent said the same of Scott and 31 percent said that of Graham.

“Most incumbents have a 're-elect regardless' number in the 30s, so the governor's numbers are quite strong,” Woodard said. “That cannot be said about Graham, his numbers show that more than two-thirds of the base GOP voters are unhappy with him, with almost 20 percent of them saying they would not vote for him in 2014.”

The poll was taken last week and concluded Monday. Its margin of error is plus or minus 5 percent. Because the GOP base is older, the survey included mostly landlines and only 4 percent cell phone numbers, Woodard said.

Reach Robert Behre at 937-5771.