President Bush and his allies have about three months to sell the public on his proposals to change Social Security (search), the chairman of the Senate Finance Committee (search) says, as Republicans continue their search for Democrats who might come aboard.

Bush was in Nebraska, Arkansas and Florida on Friday pitching his plan, trying to pressure Democratic senators from these states.

The centerpiece of his plan would divert some payroll taxes into private accounts that could be invested in the stock market. That could lead to higher returns, though the transition would cost more than $1 trillion. Other measures, still unspecified, would be needed to bring the Social Security system's long-term finances into balance.

Proponents agree that any overhaul plan will need bipartisan support if it is to pass Congress, particularly in the Senate, where Democrats can block measures and require backers to find 60 votes to move forward.

The key to winning Democratic support is educating the public about Social Security's financial problems and explaining how personal accounts would work, said Sen. Charles Grassley (search), chairman of the Finance Committee, which will handle the legislation.

"The length of the window for the education process might be 90 days," he told Iowa reporters this week. "If we don't see some grass-roots organizing and change of public opinion after 90 days, it's going to discourage people in Congress from moving ahead."

There is a growing consensus that the legislation will be tackled first by the Senate. While united House Republicans could push a measure through their chamber, many fear they could wind up casting politically risky votes only to see the legislation die in the Senate.

Several Republicans have voiced opposition to or skepticism about the Bush plan.

Not one Senate Democrat has come out in favor of private accounts, though Sen. Ben Nelson of Nebraska says he's open to the idea.

"I recognize that if I'm going to represent the people of Nebraska, I've got to represent the 66 percent who voted for President Bush," he said in an interview this week. "I haven't said absolutely no to anything."

In traveling to Nebraska Friday, Bush was aiming squarely at Nelson, telling his audience in Omaha: "I'm proud that Sen. Ben Nelson is here. He is a man with whom I can work, a person who is willing to put partisanship aside to focus on what's right for America."

Much of the work in the Senate toward a bipartisan bill is being led by Sen. Lindsey Graham, R-S.C., who is preparing to introduce a bill based on conversations with Democrats.

Graham has met with Democrats, including Sens. Nelson, Max Baucus of Montana and Blanche Lincoln of Arkansas — all targets of Bush's two-day, campaign-style swing — as well as Joe Lieberman of Connecticut.

Graham said in an interview Friday that his legislation will include personal accounts much like those proposed by Bush, with minimum benefits guaranteed for those who earn less than $35,000 per year. The transition to the new system would be paid for partly by temporarily increasing the amount of income that is subject to Social Security taxation. As is, any earnings over about $90,000 are not taxed; Graham would lift that cap.

He said that would give the system enough money that Congress could actually modestly cut the tax rate for those who earn less than $90,000.

Graham would address the traditional system's long-term financial problems by cutting benefits for all but low- and moderate-income workers by changing the way benefits are calculated.

"My Democratic colleagues will need to be convinced any new system is responsible and is progressive," he said. "My goal has to be to protect those who need Social Security the most."

Graham agreed with those who say that Bush gave Americans the dessert — personal accounts — but none of the vegetables needed to make them work.

"I've given you a balanced meal that's low-fat and will be good for you," Graham said.

The key now, he said, is for the president to continue convincing people the problem is real.