WASHINGTON — As Congress and the Bush administration scramble for accord on a plan to jumpstart the ailing economy, Mayor Bloomberg is deriding the consensus proposal for a stimulus package as a shortsighted “quick-fix” that will have little longterm benefit.

Mr. Bloomberg arrived here tonight to accept an award from the U.S. Conference of Mayors, and he doused ice water on the rare burst of bipartisanship that has brought together Democratic leaders and the White House to hammer out an economic stimulus plan.

The $145 billion proposal under negotiation centers around providing several hundred dollars in tax rebates in a bid to spur the economy — a plan that Mr. Bloomberg said could “modestly benefit Americans” but would not “make much of a difference” overall because of the high deficits the government has already run up.

“We can’t borrow our way out of this. The jig is up,” the mayor said in prepared remarks to the conference. “It’s time to start getting our house in order, which I believe starts with a simple idea: Making decisions based on the business cycle instead of the election calendar.”

Mr. Bloomberg was to speak hours after the Dow Jones Industrial Average rallied for a nearly 300-point gain, ending a volatile day that saw stocks plummet in the early hours of trading.

Invoking an oft-repeated quote from President Kennedy, Mr. Bloomberg contrasted what he described as “reckless” spending in Washington with his own record in New York, characterizing as prescient his decision to use surplus funds accrued in recent years to pay down future deficits and establish a trust fund for municipal retirees.

“John F. Kennedy told us, ‘The time to repair the roof is when the sun is shining.’ That’s what many of us in this room did,” Mr. Bloomberg said. “We used the good times to save for the future and pay down debt. And when the storm clouds started gathering last year, we tightened our belts.”

“But in Washington,” he said, “they did exactly the opposite. They spent most of this decade running up bills with reckless abandon and when the economy started heading for the ditch, the special interest give-aways got even bigger.”

The mayor offered a farming analogy to the crowd of urban leaders. “They ate the seed corn without worrying about the next year’s harvest,” he said. “Well, the next year is here, and the seed corn is gone. All we’ve got is a bunch of IOU’s.”

Mr. Bloomberg called for a combination of short-term and long-term measures to respond to the subprime mortgage crisis and shore up the economy. He stopped short of backing a full government bail out for either borrowers or the mortgage industry, but he also criticized the centrality of tax rebates in the current plan. “What good is a rebate going to do for a family who’s about to lose their home?” he said. He suggested financial counseling and subsidized loans for people trapped in bad mortgages.

Mr. Bloomberg endorsed New Deal-style federal investment in infrastructure projects that states and cities couldn’t afford, saying it would create jobs and build a foundation for the future. Congressional Democrats have also proposed infrastructure spending as a way to boost the economy. Warning against pork-barrel projects, Mr. Bloomberg singled out for praise a bipartisan plan for an “infrastructure bank” put forward by Senator Dodd, a Democrat of Connecticut, and Senator Hagel, a Nebraska Republican who has been the subject of speculation as a potential running mate of Mr. Bloomberg.

The mayor joins several presidential candidates in putting out economic stimulus proposals, but he did not offer the specifics in policy details and cost that other plans have included.

Mr. Bloomberg spoke as House Democrats and Bush administration officials were trying to finalize an agreement on their stimulus package, which would include an extension of unemployment benefits and an increase in food stamp benefits in addition to the rebates for taxpayers promised by the president.

Led by the chairman of the House Ways and Means Committee, Rep. Charles Rangel of Harlem, Democrats were also pushing for more aid targeted to low-earning Americans who do not pay income taxes.

While party leaders, including Senator Schumer, have said Democrats would not draw a “line in the sand” on the issue, Mr. Rangel rushed out a statement this afternoon after reports that Republican leaders were balking at aid for non-taxpayers.

“Congressional leaders remain committed to reaching and passing a bipartisan stimulus package,” Mr. Rangel said, “but we must follow the guidance of so many economists who have said — with great clarity — that this package must put money back into the hands of the middle- and lower-income families who will then spend it directly into our economy.”

Republican leaders were facing mounting pressure today from a coalition of fiscal hawks in the House, who announced their own stimulus proposal that centered on corporate tax cuts and other breaks for businesses instead of rebates for taxpayers.

Members of the Republican Study Committee criticized rebates as unnecessary and politically motivated. “If spending was the way to create prosperity, we would never have a recession,” Rep. Paul Ryan of Wisconsin said. “The fear is that we will pass a package that’s good politics but isn’t good policy.”

Rep. Michael Pence of Indiana said plainly there was disagreement in Republican ranks over the stimulus package, and several Republican lawmakers said they may not vote for the final package.