On the same day House Republicans launched a new attack charging Democrats with "raiding" Social Security to fund spending programs, congressional analysts revealed that the GOP's own spending plan for next year would siphon at least $18 billion of surplus funds generated by the retirement program.

Yesterday's report by the nonpartisan Congressional Budget Office seemed to undermine a concerted GOP effort to blame President Clinton for excessive spending and gain the high ground in the high-stakes political battle over Social Security. Indeed, only hours before the report was released, House GOP leaders unveiled a national advertising campaign vowing to "draw a line in the sand" in opposing Democratic spending initiatives that they said would eat into the Social Security surplus.

But in a new analysis, CBO Director Dan L. Crippen shows that lawmakers writing the spending bills that would fund government next year have already used up billions of dollars of funding beyond what they were supposed to spend under existing budget restrictions.

As a result, he shows, lawmakers will have to dip into the projected government surplus next year of $167 billion to fund programs at the level they are targeting. Because almost all of that surplus will be created by extra money rolling into the Social Security program, Crippen suggests that as much as $18 billion will have to be drawn from the retirement program.

That is up from an August CBO estimate that showed Congress on the way to spending $16 billion of the Social Security surplus, but it does not include the extra spending lawmakers are likely to approve for hurricane and earthquake relief, restoring cuts in Medicare and other needs that could drive the number even higher.

The country has more than enough surplus funds to accommodate the new spending plans under consideration on Capitol Hill, but the CBO numbers are likely to sharpen the intensifying political debate over Social Security. Although the government has routinely tapped Social Security to fund other agencies in years past, both parties have elevated protection of the retirement program to the highest priority this year.

"What the Republicans are protesting in their ad campaign they already are guilty of themselves, and have been for two months now," said Rep. John M. Spratt Jr. (S.C.), the ranking House Budget Committee Democrat who requested the CBO study. "They're . . . invading the Social Security surplus, and these are conservative numbers."

But one GOP lawmaker said the CBO numbers are premature because Congress has yet to complete work on all the 13 spending bills, implying that the numbers could change. "To somehow suggest that CBO says the funding level is going to be this or that for fiscal year 2000 is completely hypothetical," said Rep. John E. Sununu (R-N.H.), a member of the Budget Committee.

GOP lawmakers remained defiant yesterday. "Under no circumstance will I vote to spend one penny of the Social Security surplus for anything but Social Security," House Majority Whip Tom DeLay (Tex.) said during a media event dubbed "Stop the Raid."

Although Clinton and congressional leaders have agreed to a three-week extension of Friday's budget deadline in an effort to iron out their differences over sensitive spending issues, the two sides still appear to be far apart on numerous issues. If anything, the GOP may be forced to accept even more spending -- and to dip further into Social Security -- to accommodate Clinton.

By far the biggest fight is likely to be over the huge labor, health and education spending bill, which trims or guts many of Clinton's education initiatives, including his call for the hiring of 100,000 new teachers. The Senate began debating its version of the bill yesterday and voted 54 to 44 to kill an effort by Sen. Patty Murray (D-Wash.) to restore funding for the hiring of more teachers. Instead, senators approved a plan providing $1.2 billion that states could use for hiring teachers or other education goals.

The House Appropriations Committee is scheduled to vote today on what the administration considers a far more draconian version of the bill, and there is certain to be a major dustup not only on funding levels but also on how Republicans intend to pay for the additional spending in the bill.

In an effort to keep from drawing on Social Security, House Speaker J. Dennis Hastert (R-Ill.) outlined a plan to delay the earned income tax credits to the working poor to save $8.7 billion from the bill next year.

Republicans defended the measure, saying that it would encourage better monthly planning by the beneficiaries. But critics said it would create undue hardship on people struggling to stay off welfare, and senators are balking at the idea.

Hastert has been under pressure from some of his House colleagues not to make significant concessions to the White House, but criticism seemed to recede after the speaker delivered an unequivocal declaration yesterday that Republicans would safeguard the Social Security surplus.

Meanwhile, White House Chief of Staff John D. Podesta, who addressed Democratic lawmakers yesterday morning, called the GOP's spending approach "crazy" and said "the budget process is headed toward chaos."

Overall, Congress made little progress in completing work on the overdue spending bills. Faced with opposition from both Democrats and antiabortion Republicans, House leaders were forced to postpone a vote yesterday on the foreign operations spending bill.

The agriculture budget bill was also held up, as GOP leaders scrambled to line up enough signatures to force it out of a contentious conference committee. Yesterday, Democrats as well as several Republicans accused the GOP leadership of shutting down the committee in order to kill a provision lifting trade sanctions on Cuba.

Staff writers George Hager and Michael Grunwald contributed to this report.