Richard Charter, an environmental activist with New York-based Environmental Defense, said oil and gas companies have been targeting South Carolina's offshore deposits as gas prices rise and dependence on international energy increases.
About 90 percent of America's coastal acreage is federally protected.
Congress enacted the first moratorium on new offshore leases in 1981, expanding its reach on several occasions and renewing it every year since.
But environmental advocates sought stronger measures.
"One year at a time is a dangerous way to protect your coast," Charter said.
A separate ban was put in place by President George H.W. Bush in 1990 and extended by President Bill Clinton in 1998; it expires in 2012.
Now, legislation is circulating in both the Senate and Congress to lift the restrictions that have barred exploration in waters like those off South Carolina's shores.
"The two mechanisms that have protected Hilton Head ... are under direct attack," Charter said.
One bill introduced by Sen. Lamar Alexander, R-Tenn., would allow governors to waive the moratoriums in exchange for cash from the federal government.
Another proposal, the State Enhanced Authority for Coastal and Offshore Resource Act -- or SEACOR -- is making its rounds in the House.
Currently in draft form, it would strike down the congressional moratorium on exploration and pay states if they allowed drilling.
The American Gas Association, according to executive director Tony MacDonald, recently had a number of lawmakers at its Washington office to hear the group's arguments in favor of SEACOR.
Such bills stand on better footing than ever before because, some say, Washington is becoming friendlier to energy exploration.
They point to Congress's decision earlier this year to allow mineral exploration in Alaska's Arctic National Wildlife Refuge.
Environmentalists like Charter say they're also worried by efforts like those of Rep. John Peterson, R-Pa.
His proposed provision in the House energy bill would have loosened restrictions on offshore drilling.
Peterson withdrew his proposal before the House passed the energy bill Wednesday.
South Carolina's lawmakers are not unified about whether exploration makes sense for the state's future.
A spokesman for Gov. Mark Sanford said the governor is deferring to federal lawmakers on the issue while the legislation is still taking shape in Washington.
Sen. Jim DeMint, R-S.C., one of the lawmakers to whom Sanford is deferring, offered mixed reviews on exploration off the state's shores.
"Oil drilling should be off the table as far as the South Carolina coast is concerned," DeMint said.
Still, the senator said he was not necessarily opposed to drilling for natural gas because much of it could be done underwater and therefore not produce "visual pollution."
A Senate presentation by Alexander, DeMint said, had convinced him to be more open-minded about natural gas exploration, though he said his stance is not final.
Sen. Lindsey Graham, R-S.C., however, isn't drawing the distinctions that have shaped DeMint's outlook.
"He's been no fan of drilling off our coastline where millions of people live and recreate," said Wes Hickman, Graham's spokesman.
Rep. Joe Wilson, R-S.C., said he also opposes changes that would affect the coastline.
"I would not favor lifting the moratorium," he said. "The coastal areas, particularly South Carolina, should be protected."