Washington ? Tested before taking power, President-elect Barack Obama privately delivered a pre-inauguration veto threat to fellow Democrats on Tuesday, saying they would not deny him use of the remaining $350 billion in federal bailout funds.

Obama coupled his threat with a promise to revise elements of the original bailout program that have drawn widespread criticism, pledging that billions will go toward helping homeowners facing foreclosure. Several Democrats said his commitments, to be made in writing, would be enough to prevent an embarrassing pre-inauguration drubbing for the president-elect when the Senate votes this week.

“This will be the first vote that President-elect Obama is asking us for. I’ll be shocked and I’ll be really disappointed if he doesn’t get it,” said Sen. Joseph Lieberman, an independent Democrat from Connecticut.

“This is a new beginning.”

Behind closed doors, Obama also urged lawmakers to act quickly on the massive economic stimulus measure that his aides have been negotiating with congressional officials. The legislation will blend federal spending with tax cuts, and could reach $1 trillion in size, a measure of the nation’s economic woes.

Several Democratic officials described a bill very much in flux. They said lawmakers were discussing allocating as much as $80 billion over two years to help shield schools from the impact of state budget cuts and roughly $40 billion for traditional anti-recession transportation programs such as highway and bridge construction.

Additionally, they added that there was money tentatively set aside to fund a $25-a-week increase in unemployment benefits as well as a 15 percent boost in food stamp benefits. There was support in the Senate for funds to upgrade military barracks, as well. The officials spoke on condition of anonymity, saying they were not authorized to disclose details.

Democratic leaders in the House and Senate hope to have the legislation ready for Obama’s signature by mid-February, and House Speaker Nancy Pelosi and Senate Majority Leader Harry Reid, D-Nev., held a late-afternoon meeting on it.

“We’ve made great progress, and we fully intend to meet our deadline,” Pelosi, D-Calif., told reporters. She disclosed no details.