WASHINGTON — Senate Republicans on Friday blocked a plan by Democrats to pump $56 billion in government spending into the economy through public works projects, help for the jobless and money for states struggling with their Medicaid bills.

The 52-42 tally fell well short of the 60 votes needed to defeat a GOP filibuster. The White House promised a veto anyway, saying the measure would not work and would cost too much.

The House was expected to have better luck with a companion $61 billion House plan later in the day.

The bills follow a bipartisan plan enacted this winter that shipped $600-$1,200 tax rebate checks to most individuals and couples and awarded tax breaks to businesses investing in new plants and equipment.

With the economy still sagging, Democrats have long pressed for a follow-up plan that focused on more spending to extend unemployment benefits, boost food stamp payments and build infrastructure projects like roads, bridges, water and sewer projects and school repairs.

The idea, predictably, got no interest from President Bush and his GOP allies in Congress, and the practical impact of Friday's votes would be to add fodder to the Fall campaign. Several Republicans with tough re-election bids voted for the measure, including Gordon Smith of Oregon, Elizabeth Dole of North Carolina and Norm Coleman of Minnesota broke with their party to embrace the legislation.

"Record spending that could lead to record tax increases or higher deficits will not advance our economic recovery," the White House said in a statement.

The House plan seems more focused on spending that would have an immediate impact on job creation while the Senate measure contains a wish-list of items long-sought by members of the Appropriations Committee, including money to provide U.S. Capitol police with new radios, accelerate NASA's development of a new space vehicle and move the Department of Homeland Security to a new headquarters.

Democrats contend that with the administration insisting on a $700 billion bailout for Wall Street holders of toxic mortgage securities, President Bush should join them in providing federal help to the middle class and the poor. They cited studies by economists that say providing money — through food stamps and unemployment insurance — to people likely to spend it immediately has a proven record of boosting the economy.

"It injects money into infrastructure projects to create jobs directly and generate new economic activities," said Sen. Tom Harkin, D-Iowa. "We get the biggest buck stimulus-wise ... by expanding food stamp benefits. That's the best. The second best, extending unemployment benefits."