Democratic leaders accepted a deficit-reduction deal they did not like, and that ultimately could not be sold to their rank and file, out of fear of President Bush's popularity and the threat of guerrilla warfare by conservative House Republicans, Democratic sources said yesterday.

The basis of their miscalculation in promoting a plan that even House Majority Leader Richard A. Gephardt (D-Mo.) told colleagues he "detested," according to one informed source, was their belief that "the consequences of no deal would serve Republican strategy more than the consequences of a relatively bad deal."

Concessions made to conservative Republicans in the final days of negotiations, sources said, came as the Democratic leadership realized that a Democratic alternative budget plan that met many of the concerns of the House could not win a majority in the Democratic-controlled Senate.

But even more intimidating was the prospect that a failure to reach agreement would produce governmental collapse, allowing Republican conservatives, led by House Minority Whip Rep. Newt Gingrich (R-Ga.), to launch a "scorched earth," anti-Washington campaign strategy that would defeat more Democratic incumbents than Republicans this year and in 1992.

"No one is served better by chaos than Gingrich and his allies," a Democratic strategist said. Insofar as the failure to manage government could be blamed on the Democratic-majority Congress, Democrats would be likely to suffer more from a "throw the bums out" voter mentality, he explained.

This prospect was so daunting to the Democratic leaders that they accepted a budget package that placed a smaller burden on the rich than on the middle and and lower-middle classes.

"For weeks we were dealing with proposals that had a clear progressive tilt," another Democratic source involved in the negotiations said. "In the last four days, it was like a fat kid sat on the Republican end of the see-saw. Our side began to cave, and those progressivity charts the Ways and Means Committee staff kept putting together suddenly began to become regressive."

The willingness of the Democratic leaders to accept a package that the staff of both the Joint Tax Committee and the Ways and Means Committee found to place a heavier burden on the working and middle classes than on the wealthy blew up in the negotiators' faces when the proposal was made public.

"The fundamental mistake," said Rep. George Miller (D-Calif.), "was they put together a summit of the 1980s and this is the '90s. The newspapers were laying out the content and people were furious . . . . These guys acted like special interests and they were trying to sell it as the public interest and it was a gross mismatch. This summit may end the '80s in terms of wheeling and dealing and greed."

Among the Democratic concessions in the final four days of the closed-door budget negotiations were a requirement that laid-off workers would have to wait two weeks before collecting unemployment and a sharp reduction in the amount of money to be invested in a tax credit for the working poor. These items, combined with proposed beer and gasoline taxes, and clearly regressive dollar increases in Medicare premiums and deductibilty, made liberal Democrats see the budget package becoming a direct assault on working men and women, and on their parents.

Democratic budget summit bargainers finally lost their nerve when they realized they did not have the votes to win Senate approval of a Democratic budget alternative, according to sources.

If the Democrats were going to to call the Bush administration's bluff, the House and Senate wings of the party had to be able to use their majorities to pass a Democratic version meeting the requirements of $500 billion in deficit reduction over five years.

A quick head-count showed that the combination of conservative southern senators and at least three Democratic northern senators in reelection fights precluded approval of proposed tax hikes and spending cuts, virtually guaranteeing an embarrassing Senate defeat.

The budget agreement, and the process used to achieve it, also infuriated members, particularly committee chairmen and members of key committees like Ways and Means and Energy and Commerce, because it locked them out of the bargaining.

Seven of the 13 Appropriations subcommittee chairman -- known as the "Cardinals" -- voted against the resolution, including the chairman of the full committee, Rep. Jamie L. Whitten (D-Miss.), and the No. 2 Democrat, Rep. William H. Natcher (Ky.).

Far from being chagrined at the spectacle of the failure of the Democratic leadership, many members who opposed the plan were proud and elated yesterday. "What happened {Friday} night is that congressmen decided they want to be congressmen again," Rep. Mike Synar (D-Okla.) said. One-hundred forty-nine House Democrats defied leaders, contributing to the resolution's 254 to 179 defeat.

House Speaker Thomas S. Foley (Wash.), one of the Democratic negotiators, said the vote was "absolutely not" a referendum on the leadership.

"The budget summit wasn't popular, but this doesn't constitute any kind of rejection of the leadership, any more than this constitutes the rejection of the president," he said.

Most members reported overwhelming opposition in their districts to the package. The House vote, said Rep. Steny H. Hoyer (D-Md.), who voted for the package, reflected on a decade in which voters have come to believe they can deal with the deficit without pain. "We've been Reaganized," Hoyer said. "We've had a psychology the last 10 years that it is easy, but raising taxes and cutting entitlements isn't easy."

Rep. Mickey Edwards (R-Okla.) said the defeat grew out of a flawed process. "There shouldn't have been a summit in the first place," he said. "Otherwise, why did they elect any of us? Some votes against yesterday were votes against the process . . . . This is a separate, independent institution. I'm not a package you can purchase at a grocery store."

Some Democrats, and even some Republicans, took some comfort in the belief that Gingrich, despite his victory, seems weakened.

"The biggest single loser in this is Newt Gingrich," said Rep. Pat Williams (D-Mont.). "When Bob Michel leaves, that's when he pays." Michel, another of the budget negotiators, is the House minority leader.

"If it was calculated to get him the leader position, it backfired," said Rep. John G. Rowland (R-Conn.) of Gingrich.

"He's got to have hurt himself," Hoyer said. "The president has to be angry with him. He gave us heartburn. He gave his own party heartburn."

Hoyer called a defeat of Gingrich in the whip election "an outcome to be devoutly prayed for."

Staff writer Dan Morgan contributed to this report.