Democrats are calling for speedy passage of an economic stimulus bill as the U.S. economy continues to shrink and shed jobs.  Yet many Republicans say they will not support the legislation, despite efforts by a few moderate Republicans to hammer out some common ground on the roughly $800-billion plan.

The Senate is expected to approve this week its version of the stimulus package aimed at creating or saving three to four million jobs.  U.S. President Barack Obama has made it his priority this week to build momentum for the plan by arranging a series of campaign-style events in Indiana and Florida.

One of the president's chief economic advisers, Lawrence Summers, appearing on the Fox News Sunday program, painted a bleak picture of the state of the economy.

"We've got to give this economy some help," said Lawrence Summers. "The Senate bill, the House bill, the overlap is 90-plus percent.  We've got to work through the differences, find the best bill we possibly can, and get it in place as quickly as possible to contain what is a very damaging and potentially deflationary spiral."

The biggest differences between the two bills concern tax cuts - the  Senate bill has allotted about $100 billion more for them - and  aid to state governments. 

But Republican support for either version remains scant.  Republicans are advocating a much smaller stimulus package that focuses mostly on tax cuts and spending on infrastructure.

Republican Senator John McCain, a former presidential candidate, told CBS' Face the Nation he will not support the bill.

"I think this can only be described as generational theft." said John McCain. "We're going to have, already, $1.2 - trillion deficits, by estimates, and it's just begun.  We're going to amass the largest debt in the history of this country by any measurement, and we're going to ask our kids and grandkids to pay for it."

McCain says the measures being taken are much larger than those taken during the Great Depression.  But Summers, in another appearance on ABC's This Week, sharply disputed these historical comparisons.

"Those who presided over the last eight years, the eight years that brought us to the point where we inherited trillions [of] dollars of deficit, an economy that is collapsing more rapidly than in any time in the last 50 years, don't seem to be in a strong position to lecture about the lessons of history," he said. "We need an approach that is very different than the approach we had that brought us to this point."

Summers says that is precisely what the president's stimulus package is providing.  He says the Department of Labor's report Friday that 600,000 jobs were lost in January alone is proof that fast action is needed.