U.S. Sen. Lindsey Graham’s approval rating among Republican voters in South Carolina has plunged by fourteen points in just two months – evidence of growing dissatisfaction with his increasingly leftward ideological bent.

According to the results of a new Winthrop University poll, Graham’s approval rating among GOP voters in the Palmetto State is 57.5 percent – down from 71.6 percent in February.

“This drop corresponds to the entry of two vocal challengers, and discussion of a third, into the primary race against him,” the Winthrop pollsters note.

It also comes on the heels of Graham’s high profile attack against fiscally conservative U.S. Sen. Rand Paul last month.

Among all registered voters in South Carolina, Graham’s approval rating stands at 43.9 percent – while 39.8 percent disapprove of his performance.

Graham has already drawn a pair of socially conservative challengers for next summer’s Republican primary election – S.C. Sen. Lee Bright (R-Spartanburg) and former congressional candidate Richard Cash.

Meanwhile, contemplating a bid is Nancy Mace – the first woman to graduate from The Citadel (South Carolina’s military college) and a co-owner of this website.

The Winthrop poll surveyed 1,069 South Carolina adults from April 6-14. It has a margin of error of plus or minus 3.5 percentage points.