“Obviously you don’t want to do something to lose votes,” said Senator Kent Conrad, Democrat of North Dakota, who was among Senate Democrats who huddled Tuesday to discuss possible alterations in the proposal.

Speaker Nancy Pelosi was noncommital about the new Senate plan Tuesday night, but other Democrats said it might be difficult to reject given the crisis and the array of tax breaks. “The Senate will vote tomorrow night, and the Congress will work its will,” Ms. Pelosi said. .

House officials spent much of Tuesday considering their own changes, including an extension of unemployment pay and a $1,000 tax credit for less affluent homeowners.

But those plans are not likely to advance given the Senate decision. While the Senate left the door open slightly to other additions to the bill, such revisions would need the agreement of the full Senate, and the House proposals were likely to be blocked by Senate Republicans.

“Opening this up all over again to other things may doom it,” Mr. Dodd cautioned.

The Senate proposal would cost more than $100 billion and extend and expand many individual and business tax breaks, including tax credits for the production and use of renewable energy sources, like solar energy and wind power.

The bill would also extend the business tax credit for research and development, expand the child tax credit, protect millions of families from the alternative minimum tax and provide tax relief to victims of recent floods, tornadoes and severe storms.

Members of the House and the Senate said the bill would create tens of thousands of jobs and reduce the nations’ dependence on foreign oil. But the two chambers have been at odds over whether and how to offset the cost of extending the many tax breaks covered by the legislation. The major obstacle has been Representative Hoyer of Maryland and other centrist Democrats.