WASHINGTON (AP) While a proposed economic stimulus plan could boost this year's deficit by $100 billion, political leaders believe the flood of red ink is worth the cost if it keeps the country from falling into a prolonged recession.

Worries that any recession could be a severe one, far surpassing the last two mild, brief downturns in 1990-91 and 2001, have captured the attention of President Bush and other politicians, especially in an election year with the White House up for grabs.

Bush and House leaders reached a deal in record time last week that would provide $150 billion in economic stimulus through tax rebates that will go to 117 million families and temporary tax breaks for businesses.

The House is rushing the proposal to a vote this week and Senate Majority Leader Harry Reid said he hopes to have the package approved by the Senate and on the president's desk by Feb. 15.

While those plans could fall victim to desires by Senate Democrats to add support for unemployment benefits and food stamps items that got left out of the House version the administration is stressing the need for speed given the recent economic data.

The Federal Reserve, alarmed by a global sell-off of stocks, cut a key interest rate by the largest amount in more than two decades in an emergency move last week and could cut rates again when the Fed holds a regularly scheduled meeting this week.

Concerns have mounted with a cascade of bad news on the economy, from multibillion-dollar losses at some of the nation's biggest banks and investment houses to soaring mortgage defaults and a continued plunge in housing.

Many economists believe the proposed stimulus package contains the right mix of fast-acting relief that will have an impact, if not in averting a recession, at least in limiting the severity of any downturn.

"Most stimulus packages have been totally useless in the past because they didn't get through Congress until the recession was already over," said David Wyss, chief economist at Standard & Poor's in New York. "This time we may be moving quickly enough to actually make a difference."

The rescue effort will not be without its own costs. Economists estimated that the deficit for this year will be between $100 billion and $120 billion higher because of the stimulus package, primarily from the cost of the refund checks. Business tax breaks will reduce government revenue by a smaller amount this year; other costs from the business relief will take effect next year.

Economists at Global Insight, a private forecasting firm in Lexington, Mass., are projecting that this year's deficit, with the stimulus package included, will hit $400 billion. That would be the second highest imbalance on record in dollar terms, surpassed only by the all-time high of $413 billion in 2004.

Even without the stimulus package, the Congressional Budget Office is forecasting that the deficit for 2008 will jump to $219 billion, up from last year's $163 billion. And CBO said its new estimate did not include still unapproved outlays for the wars in Iraq and Afghanistan, which will probably push the deficit to around $250 billion.

Adding a stimulus package will make that imbalance go even higher, but was seen by many economists as critical insurance against a severe downturn.

"Doing nothing and running the risk that the economy will slide away into a deep recession would cost the Treasury even more in lost tax revenues and increased spending," said Mark Zandi, chief economist at Moody's Economy.com.

Zandi said he believed the stimulus package that House negotiators have approved will be enough to boost economic growth by 1.5 percentage points in the second half of this year and by about 0.5 percentage point in the first half of 2009. That should translate into an additional 700,000 jobs over what the economy would have created during that time period, Zandi said. The unemployment rate will still rise from the current 5 percent to around 6 percent, but not the 6.5 percent it would hit without the stimulus package, Zandi said.

Other analysts also are forecasting a boost in growth and jobs from the package, due to increased consumer spending which accounts for two-thirds of the economy and increased business investment to expand and modernize in response to the tax incentives.

Douglas Elmendorf, a senior fellow at the Brookings Institution and formerly an economist at the Federal Reserve, said he believed that economic growth this year will be about 0.7 percentage point higher than it would have been without the stimulus, although he said that may not be enough to keep the country out of a recession.

Sara Johnson, a senior economist at Global Insight, a private forecasting firm, said she believed the gross domestic product would decline in the first and second quarters of this year the classic definition of a recession but that GDP would grow at a robust rate of 3 percent in the July-September quarter, the period when consumers will be spending their rebate checks.

While this is the first stimulus package being put forward, it may not be the last if the slowdown becomes more severe. And the Fed, which has already cut a key interest rate four times, is expected to provide more rate relief if needed to shore up confidence.

"You can construct some very dark scenarios given all the uncertainty that exists over just how big the problems in the financial system might turn out to be," Zandi said. "That is why what policymakers have done is so important to try to shore up confidence."