"We will not raise payroll taxes to solve this problem," Mr. Bush said Thursday as he met in the Oval Office with a panel of advisers on the Social Security issue.
Mr. Bush renewed his call for legislation that would let workers create private retirement accounts within the government-run program.
The president sidestepped questions about whether the nation can afford to borrow in order to confront a shortfall in the trillions of dollars.
"I will not prejudge any solution," he said.
At a time of record deficits, estimates of the money needed range from $1 trillion to $2 trillion or more over a decade. Mr. Bush said the total unfunded liability is $11 trillion.
"Does this country have the will to address this problem? I think it must," Mr. Bush said, sitting next to Treasury Secretary John Snow and the members of his panel.
"There is a recognition among the experts that we have a problem, and the problem is America is getting older and that there are fewer to pay into the system to support a baby boomer generation which is about to retire," Mr. Bush said. "We have a responsibility to solve problems before they become acute."
The call for private accounts is the most controversial element of Mr. Bush's vision for a remodeled Social Security. Administration officials had signaled previously that they were leaning toward borrowing to finance the changes, rather than raising taxes.
A presidential commission in 2001 proposed allowing individuals to place up to 2 percent of their payroll into a private account to be invested for retirement. Any such plan depends on a large infusion of cash to replace the tax money that would otherwise fund the government benefits.
Mr. Bush and lawmakers of both parties generally agree on the need for eventual changes in Social Security to shore up its solvency. But they disagree sharply on the urgency of the task and the wisdom of letting workers channel a portion of their payroll taxes into private accounts.
Workers generally pay a 6.2 percent payroll tax on income up to $87,900. Their employers match the payment, and the combined tax finances monthly Social Security retirement checks.
Apart from borrowing, another option for covering costs is to increase the retirement age, which is gradually rising to 67 under legislation approved nearly two decades ago.
Mr. Bush wouldn't say how he would pay for the changes.
Though many blue-ribbon panels have tackled the Social Security issue over the years, the president said he planned to wait for the recommendations of his trustees before he seeks legislation.
"I have articulated principles in the course of my campaign that I think are important, and it's very important for those who have retired to recognize that nothing is going to change when it comes to Social Security," he said.