COLUMBIA - With a filibuster looming in the Senate to block a plan to reduce the state's income tax, Gov. Mark Sanford is worried a key piece of his legislative agenda will be scuttled before the General Assembly adjourns next week.

"There's a difference between debate and obstruction," said Sanford, who added that people are aware time is running out.

The governor's proposal moves the state's top income tax rate to 4.75 percent from 7 percent over several years. No break would be implemented in years when the state's revenues don't grow by 4 percent or more.

Critics have said the plan only benefits the top half of the state's income ladder.

"It deserves as much debate as people want to put into it on the Senate side," he said. "What we would hate to see would be for people to filibuster and people never have the chance to go thumbs up or thumbs down."

Sanford jetted to Florence, North Charleston and Aiken on Monday to visit with small-business owners, who the governor said would benefit from the plan, and urged them to contact their senators.

Sen. Tommy Moore, D-Aiken, said he wants more explanation of the plan's economic impact.

"In a time when we can't or have chosen not to fund public education and Medicaid, then what does that mean as far as the general fund?" Moore asked.

The proposal won key support from Republican senators last week. Most of the Senate's 27 GOP members endorsed placing the Senate's version of the income-tax reduction measure onto a bill that cleared the House.

The House heavily amended the bill with a variety of tax measures, but the Senate will take everything out and insert just the Senate's income tax plan.