WASHINGTON (CNN) - To the consternation of his Democratic leadership, Rep. Robert Wexler of Florida will introduce a bill Monday that would raise the payroll tax on high income Americans to extend the solvency of Social Security without requiring benefit cuts.

Democratic leaders, who have successfully kept their party unified against President Bush's personal accounts, are privately fuming Wexler is moving ahead with his own plan. They fear Republicans will be able to spin it as a broader "Democratic plan," relying on tax increases that Republicans abhor.

"I think there are people on the Democratic side who feel that way, that this is a mistake," acknowledged Wexler's chief of staff, Eric Johnson. But he said Wexler feels Democrats have successfully demonized Bush's "privatization" plan and now need to offer their own vision to protect Social Security.

"Democrats should stake out a strong position that doesn't cut benefits," Johnson said.

Wexler will introduce his "Social Security Forever Act" at a news conference in Delray Beach, Fla. His congressional district, which includes Palm Beach and Broward counties, is home to more Social Security recipients than that of any other Democrat in the House, Johnson said.

Right now, there are no co-sponsors of the bill.

The plan would impose a 3 percent tax on all earnings over $90,000.

Currently, the 6.2 percent tax only applies to the first $90,000 a person earns each year.

Johnson said President Bush and Sen. Lindsay Graham, R-S.C.., were the first to suggest raising the payroll tax as a means to extend the solvency of Social Security.

Check out our Social Security special report.

--from CNN Congressional Producer Ted Barrett