The budget agreement negotiated by President Bush and congressional leaders drew a firestorm of criticism from conservative Republicans and considerable skepticism from many Democrats yesterday, as lawmakers from both parties predicted that it will be difficult to sell the plan to Congress.

Republicans assailed the deficit-reduction package as a "cave-in" to Democratic pressure for tax increases as an alternative to deep domestic spending cuts. Democratic critics charged that both the tax and spending provisions favored the wealthy at the expense of the middle class.

Particularly strong hostility from House GOP conservatives, who called the plan a "road map to recession" and "the fiscal equivalent of Yalta," cast doubt over whether the White House and Republican congressional leaders can persuade a majority of House Republicans to vote for the plan. The Democrats have demanded that a majority of GOP lawmakers in both houses vote for any deficit-reduction plan as the price for their support.

Reiterating that demand, Senate Majority Leader George J. Mitchell (D-Maine) said last night that "if we can't get a majority {of both parties in both houses}, then the agreement can't pass."

Several leaders said they believe the five-year, $500 billion package of spending cuts and tax increases can be passed, but only if the president and congressional leaders make an extraordinary bipartisan effort to sell it to the public as well as Congress.

"It won't be easy, but I think we can do it, although it will take strong bipartisan leadership -- and especially leadership from the president," said Senate Finance Committee Chairman Lloyd Bentsen (D-Tex.), who praised the plan's drafters for having made "the necessary but politically unpopular choices."

"It's going to be a real bear to get it passed," said Rep. Henry J. Hyde (R-Ill.).

After briefing a largely hostile House Republican caucus on the plan, Minority Leader Robert H. Michel (R-Ill.) declined to say whether he thought it would eventually win support by a majority of House Republicans, who are considered the key group in determining the package's fate. "This is just the beginning of the process," he said, noting that opposition from anti-tax conservatives came as no surprise.

Other Republicans, mostly moderates, said it is still possible to produce a majority for the plan. But some said Bush must be willing to go to the mat with conservatives on the issue of taxes, which he had vowed to oppose -- to the delight of the party's right wing -- during his presidential campaign. "It's one thing to take potshots today and another when the president talks to the people and to the members himself," observed Rep. Ralph Regula (R-Ohio), a moderate who said it will be difficult but not impossible to pass the plan.

The mood also may change when lawmakers "consider the alternative," Regula said in a reference to automatic across-the-board spending cuts. Such cuts could eventually total $105.7 billion, disrupt government services and furlough more than 1 million federal workers.

But the initial response to the plan indicated qualms, if not opposition, within senior GOP ranks in both houses. Both House Minority Whip Newt Gingrich (R-Ga.) and Sen. Bob Packwood (R-Ore.), ranking Republican on the Finance Committee, pointedly skipped the unveiling ceremony in the White House Rose Garden. Gingrich later said he was still studying the plan.

To rally support for the plan, Bush assured Democrats that he will lay aside the kind of partisan attacks he has been making in connection with the budget talks and try to "sell" the plan to the American people.

For their part, Democratic congressional leaders put Congress on a tight leash in dealing with the plan by agreeing to a schedule that effectively locks the budget plan to the fate of other must-pass measures needed for the government to retain legal spending authority.

The problem for both parties is that the budget agreement hits directly at some of their most cherished political tenets, including opposition to tax increases for Republican conservatives and cutbacks or freezes in social welfare programs for Democrats. Many Democrats also criticized the tax components of the package, arguing that higher excise taxes -- especially the proposed 12-cents-a-gallon hike in taxes on gasoline -- would have a largely regressive impact by hitting poor and middle-income people the hardest.

But the strongest criticism came from members of the president's own party.

"To me, this is the fiscal equivalent of Yalta," said Rep. Chuck Douglas (R-N.H.), referring to the pact among Allied leaders in World War II that conservatives say was responsible for postwar Soviet domination of Eastern Europe. He said he would rather see the automatic spending cuts of the Gramm-Rudman-Hollings law take effect than the tax increases proposed in the plan.

"It looks like a road map to recession, as far as I'm concerned," said Rep. Dana Rohrabacher (R-Calif.). "I don't think it's a compromise. I think it's a cave-in to the Democratic liberal big spenders."

Republican moderates also expressed dismay. "If they're savaging Medicare, it's going nowhere," said Rep. Marge Roukema (R-N.J.). "Deficit reduction on the back of the elderly sick? This is madness."

Although House Democrats were asked by their leaders during a caucus to hold their fire for at least 24 hours, some expressed strong misgivings before the caucus started.

"It just leaves the richest of the rich alone," said Rep. Charles B. Rangel (D-N.Y.). "Everybody I've talked to so far has been negative," said Rep. Bill Alexander (D-Ark.). "The disquiet I have comes from the impression that the investing side of society has come out ahead of the wage-earning side," said Rep. David R. Obey (D-Wis.).

The problem with the package is that "Democrats think it's a Republican budget and Republicans think it's a Democratic budget," said Rep. Charles E. Schumer (D-N.Y.).