Washington ? A top Senate Democrat unveiled a $156 billion economic stimulus package 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 today 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 scheduled a Wednesday vote on a bill with the add-ons, which would send rebates even to the wealthiest taxpayers.

“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.

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 House leaders. People would still receive an extra $300 per child.