Updated

A top Senate Democrat unveiled a $156 billion economic stimulus package on Monday that awards rebates to senior citizens living off Social Security and extends unemployment benefits, setting up a clash with the White House and House leaders pushing a narrower package.

As the House planned a vote Tuesday on a plan that would speed rebates of up to $600 to most income earners — more for couples and families with children — Senate Finance Committee Chairman Max Baucus slated a Wednesday vote on a bill with the add-ons.

"My proposal will give America's seniors the same rebate as any wage earner," said Baucus, D-Mont. "The White House says we mustn't slow the economic stimulus agreement down, or blow it up. I agree. We're going to improve it and get it passed right away."

The move was in defiance of admonitions from the Bush administration not to risk derailing the deal with changes, and it threatened to slow what was shaping up as an extraordinarily rapid trip through Congress for the stimulus measure. The Senate hopes to pass its version by week's end, said Jim Manley, spokesman for Majority Leader Harry Reid, D-Nev.

The president and House leaders agreed last week on a proposal to provide rebates to 117 million families and to give businesses $50 billion in incentives to invest in new plants and equipment. The goal is to help head off a recession and boost consumer confidence.

Adding rebates for senior citizens living solely off Social Security checks — who are ineligible under the plan hatched by House leaders and the White House — caused Baucus to reduce the size of the rebate to $500 for individuals and $1,000 for couples, instead of the $600-$1,200 rebate plan agreed to by Bush and bipartisan House leaders.

President Bush planned to use his State of the Union address on Monday night to call on Congress to move quickly on the agreement, the White House said.

"The president is concerned about efforts that would delay or derail the bipartisan package that was negotiated with House leaders," White House spokesman Tony Fratto said. "The Senate is threatening to create partisan conflict by trying to put in additional programs."

Still, pressure from the elderly and labor unions — both politically potent forces — is spurring senators from both parties to call for the extras.

The House plan leaves out some 20 million seniors, according to the AARP.

The Senate measure includes a 13-week extension of unemployment benefits and a 26-week extension in states where the unemployment rate exceeds 6 percent.

The White House has warned against tinkering with the agreement reached with House leaders last week.

"I don't think the Senate is going to want to derail this program," Treasury Secretary Henry M. Paulson, Bush's pointman on the deal, told CNN on Sunday. "And I don't think the American people are going to be anything but impatient if we don't enact this bipartisan agreement quickly."

Reid has said the Senate would consider adding to that plan, including extending unemployment benefits, boosting home heating subsidies, raising food stamp benefits and approving money for public works projects.

Senate Republicans and Democrats — kept on the sidelines as House Speaker Nancy Pelosi, D-Calif., and Minority Leader John A. Boehner, R-Ohio, cut the deal with Paulson last week — were eager to put their stamp on the high-profile package. Several wish-lists were floating around Capitol Hill, but the unemployment extension and rebates for seniors appeared to have the most bipartisan appeal.

The Senate measure restores a business tax break dropped from the House bill that would permit corporations suffering losses now to reclaim taxes previously paid.