DeMint is hosting the GOP primary event, which Perry was initially scheduled to attend. Local station WSPA reports that Perry's office confirms the Republican presidential contender is heading back to Texas to address wildfires plaguing the state.
(Click here for a full preview of the South Carolina forum.)
The AP reports on the Texas wildfires:
Authorities say a wildfire burning southeast of Austin, Texas, has destroyed about 300 homes and is advancing unchecked through parched ranchland along a 16-mile front.
Texas Forest Service spokeswoman Jan Amen said Monday that firefighters have been unable to begin containing the blaze in Bastrop County. The forest service says the fire has destroyed as many as 300 homes scorched more than 17,500 acres.
The fire is roughly 30 miles from Austin and is moving away from the city.
KVUE-TV in Austin reports that nearly half of the 6,000-acre Bastrop State Park has burned.
With Perry out, the list of GOP hopefuls taking part in the forum includes: Former Massachusetts governor Mitt Romney, Rep. Michele Bachmann (R-Minn.), Rep. Ron Paul (R-Texas), former House Speaker Newt Gingrich (R-Ga.), and former Godfathers's Pizza CEO Herman Cain.
According to the Washington Examiner's Byron York, Rep. Steve King (R-Iowa), who will present candidates with questions at the event, called Perry's change of plans "a big disappointment to me."
ABC News reports that the Texas governor still intends to participate in Wednesday's presidential debate in California.
UPDATE: DeMint tells ABC News of Perry's last-minute change of plans, "He has to make his own decision, but certainly we are disappointed."