That process begins in Washington this week, as President George W. Bush and Democrats in Congress start what is likely to be a nasty, months-long debate over how to fashion a budget without using Social Security tax money. Bush, who recently turned 55 (making him eligible to live in a Del Webb retirement village), returned from his Texas vacation insisting there was enough cash for all the increases he wants in defense, education and health care. The relatively nonpartisan Congressional Budget Office declared otherwise. Congress, the CBO said, would have to use at least $9 billion out of an estimated $160 billion in surplus Social Security tax receipts.

Until a few years ago, $9 billion–or $90 billion–would have been no big deal. From the days of Lyndon Johnson until midway through the Clinton years, presidents and Congress spent Social Security “trust fund” money at will, replacing it with I.O.U.s on the federal books. But in 1996 Bill Clinton took a Republican idea–stashing mounting piles of Social Security tax receipts in a “lockbox” account–and ran on it. His theme, “Saving Social Security First,” was a masterstroke, allowing him to play fiscal tightwad and FDR liberal simultaneously. Ever since, Republican and Democrats have competed for the crown of Champion Social Security Defender. “The two parties probably spent a billion dollars in advertising on it in the last two cycles,” said one top Democratic strategist.

Now everyone in Washington is locked in a “lockbox” lockbox–at a time when, many economists think, a sputtering global economy could use a jolt of extra federal spending. “A case can be made,” said Tauscher. She’d have credentials to do so. A wealthy investment banker and entrepreneur, she knows that the “Social Security surplus” isn’t going to the program at all–but rather to paying off federal debt. She represents a swing district in northern California full of well-off voters who applauded her vote for the Bush tax cut. She proposes the eventual diversion of some payroll-tax money into a stock fund run by a government board.

But Tauscher, a leader in the House, is dead set against touching a penny of the current surplus. Better to pay down the overall federal debt, she argues, reducing the nation’s credit-card balance so Treasury can borrow big time when the boomers are really old. But political combat is part of it, too: why let Bush out of the lockbox he jumped into during the 2000 campaign? “He’s in a deep hole,” crows Senate Budget chairman Kent Conrad. The Democratic Party, NEWSWEEK learned, conducted polls and focus groups in August to prepare for a new ad campaign this week. The finding: voters would rather leave the surpluses untouched than dip into them for anything else–missile defense, education and prescription drugs included. “They see the money as inviolate,” says polltaker Geoff Garin.

Especially baby boomers, who may soon make the Gray Panthers look like pussycats. Boomers are paying close attention for the first time, polltakers say, and are vehement about not touching Social Security surpluses. Suddenly, a generation known for its distrust of government is placing its faith in the essence of it. With 401(k)s shrinking and the market tanking, the solid-looking benefits of the program loom large–especially for a cohort famous for not planning ahead. Expect them to insist on full benefits, now and forever. “Most boomers never bothered writing that memo about retirement planning,” says polltaker Harrison Hickman. “But they’re used to a comfortable lifestyle, not sacrifice.”

So how will the second boomer president escape the political shackles the first one put him in? For now, Bush isn’t going to try. Let the Democrats raise taxes first, he’ll say. But if forced–as he almost certainly will be–the president will argue it’s worth dipping into the funds to avoid a recession and to bolster national security. “Bush has to stress the word security on defense,” says polltaker Frank Luntz, who counsels the GOP Hill leadership. “And he has to say that you can’t save Social Security without saving the economy first. It’s a tricky sell.” But it’s one Bush will have to try–and his generation will have to decide whether to accept.