President Clinton yesterday attacked Republicans' initiatives on Social Security, charging that their approach would do nothing to extend the life of the retirement program and promising to submit his own plan to Congress this week to ensure its solvency for 50 years.

"Americans deserve more than confusion, double talk and delay on this issue," Clinton declared in his weekly radio address, responding to repeated GOP claims last week that the Democrats were trying to "raid" the retirement program to fund new spending.

The escalating rhetoric came as both sides prepared for a final showdown this week on the budget for the federal government. Congressional Republicans have tried to use the process to position themselves as protectors of Social Security, while the Democrats have criticized the GOP for engaging in fiscal gimmickry to mask its own raid on the retirement program.

For much of the fall, the GOP majority on Capitol Hill has had a free hand to write the 13 spending bills as it sees fit, but the president has now vetoed two bills and has promised to reject several more. Assuming the Democrats in Congress stay united, Clinton hopes to use his veto pen to extract new concessions on education, hiring more police, foreign aid and the environment.

Yesterday, however, that strategy appeared at risk over the giant spending bill for the Pentagon. The measure could be an important bargaining chip for Clinton, but it is also popular in both parties -- in part because it contains money for a 4.8 percent pay raise for military personnel, the biggest increase in 18 years.

Several pro-defense Democrats, led by Rep. John P. Murtha (Pa.) and Ike Skelton (Mo.), have warned leaders that they will work actively to override a veto, and House Minority Leader Richard A. Gephardt (D-Mo.) spent part of the day quietly gauging member sentiment.

Publicly, the White House was focused on bolstering support for its plan to tap future budget surpluses to shore up Social Security. Clinton and the Democrats have traditionally used the issue as a political battering ram against Republicans, but this year the GOP has fought back by promising to fund the budget without touching Social Security payroll taxes.

Congressional Democrats have been nervous about that pledge possibly gaining political traction, and in his radio address Clinton argued that the GOP plan would do nothing to reform the Social Security system or extend its solvency beyond 2034.

"I think we can do better," the president said.

Clinton said he would submit to Congress a portion of the Social Security rescue plan he outlined early this year. That plan involves a complicated scheme to use federal budget surpluses to pay down the national debt -- and then earmarking the resulting savings from lower interest payments to shore up Social Security.

Republicans prefer a greater reliance on individual investments. Clinton's original proposal would have allowed the government to invest some Social Security taxes in the stock market, but that idea was dropped from the plan he said he would submit to Congress.

Gene Sperling, director of Clinton's National Economic Council, said Clinton's plan would enable the country to "meet our Social Security burdens later without making the next generation have to raise taxes or cut spending on necessary priorities."

Rep. J.C. Watts (Okla.), chairman of the House Republican Conference, said Republicans "will not allow the president's desire for a legacy to supersede the needs of the American people. We will not let him raid the Social Security trust fund."

Administration officials noted that Clinton made it clear to congressional leaders last week that he wanted them to consider his Social Security plan during final deliberations over the budget. They said Clinton is seriously considering vetoing the defense bill to maximize his leverage, even though a vote to override a veto could be close.

Democrats need 146 votes to sustain a veto. The House approved the defense bill 372 to 55 earlier this month, with only 47 Democrats opposing the measure.

"The president made it clear to the congressional leadership that we need to see how the numbers add up for all the big outstanding bills, including defense, and see whether the Republicans are able to propose acceptable solutions to fix the Social Security problem," said Linda Ricci, a spokeswoman for the White House budget office.

Conservative Democrats, many of whom face tough races next year, said they were reluctant to support a veto on defense. "I'd probably have to support the defense bill, because defense is pretty important in our area," said freshman Rep. Ronnie Shows (D-Miss.).

Even House Democratic Caucus Chairman Martin Frost (Tex.) has "reservations" about sustaining a veto on the bill, according to Frost spokesman Tom Eisenhauer.

But Gephardt is strongly committed to the president's veto strategy, and he told House Democrats during a caucus Thursday that if they differed with that approach they could vote him "out as leader," according to participants in the meeting.

House GOP leaders accused their Democratic counterparts of putting critical bills in jeopardy. "You still have some very honorable people who are looking at the issue and refusing to play partisan politics," Majority Whip Tom DeLay (R-Tex.) said in an interview, adding that the House would have "an excellent chance" of overriding a veto of the defense bill.

Staff writer George Hager contributed to this report.