COLUMBIA, S.C. - Gov. Mark Sanford has tapped two of his closest Washington, D.C., allies to help sell his plan to lower the state's top income tax rate in an effort to attract wealthy executives and retirees to the state.

But state some lawmakers question why the governor has invited fellow Republicans U.S. Sens. Lindsey Graham and Jim DeMint to talk about the issue Wednesday in a Charleston suburb - halfway across the state from a meeting at the Statehouse that could decide the measure's fate.

Sanford faces one of his toughest political fights to get support for his proposal to cut the state's top income tax rate to 4.75 percent from 7 percent. Its $1 billion cost when fully implemented in 10 years worries legislators.

While Sanford gathers with Graham and DeMint, a state Senate Finance subcommittee meeting in Columbia could decide what happens to the governor's proposal.

Members of that panel say they expect the bill will be derailed and replaced with a plan to give a similar break only to small business owners. It would cost about $100 million when implemented fully in four years.

Senate Finance Committee Chairman Hugh Leatherman, chief sponsor of the bill to rival the governor's plan, says he respects Graham and DeMint. Still, "it sort of seems to me like they may have their hands full up in D.C. with these issues they are dealing with," the Florence Republican said. They should "leave these state issues to the General Assembly."

"He's right," Graham said. "It's not my goal to tell the South Carolina Senate what to do or tell the governor what to do," he said. Graham said he wants to talk about how tax reductions benefit the economy.

"What Mark is trying to do - by providing across the board tax relief by changing our income tax rates - I think is a very good idea, long overdue," Graham said. If the state is going to compete economically with its neighbors, tax cuts are needed, he said.

DeMint was not immediately available for comment. He will be with Sanford to talk about how lower taxes "will help create jobs and make South Carolina more competitive," DeMint spokesman Wesley Denton said.

Sanford, Graham and DeMint served together in the U.S. House and have called on each other to rally support during tough campaigns. But this may be one fight where Sanford's longtime political allies will have less influence.

If Graham and DeMint want to get involved, they should go to the subcommittee meeting, Leatherman said. "That's where the votes will be tomorrow. I don't think there will be any votes down in the Charleston area," he said.

They'd be more effective at the subcommittee meeting than "having a grandstand in Charleston," said Sen. Scott Richardson, R-Hilton Head Island.

Leatherman's competing proposal is viewed as far more likely to succeed by legislators, particularly in the Senate, where 37 of the upper chamber's 46 members have signed on as co-sponsors.

Senate leadership appears to have a tax cut that's an appealing alternative to Sanford's bill, said Neal Thigpen, a Francis Marion University political science professor. "He just simply got outmaneuvered."

Sanford, however, isn't bereft of allies. "I hate to see the governor's plan be shuffled to the side because we embrace another plan," said Sen. John Hawkins, R-Spartanburg. Graham and DeMint can help it succeed, Hawkins said.

Graham said the work on the issue was best left to Sanford and the Legislature.

"My hope is that they can reach some compromise" and provide investment incentives, Graham said. "It's up to the Statehouse and the governor to work out their differences and I hope they can."

Sanford's proposal will help everyone in some way, said Will Folks, Sanford's spokesman.

For instance, a single person with a $35,000 would pay $350 less in taxes by the time the cuts are fully implemented in 10 years, Folks said.

Even people lower on the income ladder get something because the proposal ties state's income tax rates to inflation - sparing wages from higher taxes in the future, Folks said.

In the end, the lower taxes will help the state's economy and improve on the state's status of having the nation's fourth highest jobless rate, Folks said.