Washington ? President Bush says Social Security’s future financial shortfall is a crisis that Congress must tackle now, repeating Monday his demand for action but refusing to provide details of his top domestic priority that will cost trillions of dollars to implement.

“Don’t bother to ask me,” Bush told reporters at a year-end news conference when pressed for the specifics of his plan to overhaul Social Security to allow personal investment accounts similar to a 401(k).

Bush made clear he would not engage in a public debate about how to shore up Social Security’s $3.7 trillion, 75-year shortfall until he gives Congress “a solution at the appropriate time.” The administration has said a plan is still being crafted.

“The temptation is going to be … to get me to negotiate with myself in public. To say, you know, ‘What’s this mean, Mr. President? What’s that mean?’ I’m not going to do that,” Bush said. “The law will be written in the halls of Congress. And I will negotiate with them, with the members of Congress.”

Bush continues to spotlight the system’s future financial problems, which he calls a crisis, and the positive aspects of his plan, including allowing people to create a retirement nest egg they own and mostly control without raising payroll taxes or cutting benefits for current retirees or those nearing retirement age.

But there are questions and tradeoffs in the details. Critics accuse the White House of inventing a Social Security emergency to generate public support to help ram Bush’s plans through the Republican-controlled Congress.

Bush promised Monday to send a “tough budget” to Congress next year that maintains “strict discipline” on spending, in what budget experts and congressional sources said could be a commitment to deeply cutting some domestic programs, and possibly eliminating others.

Bush signaled that defense and homeland-security programs would continue to be sacrosanct, and likely shielded from the budget ax.

He also said he would appoint a commission to study reforming the tax code, and push to strengthen his signature “No Child Left Behind” education measure.