Other Democrats cautioned that work still had to be done, although some expressed hope a vote on the issue could be held as early as Thursday evening or Friday morning.
"While we've reached some agreement on a lot already, there are issues that are still outstanding,'' Christopher Dodd, senator for Connecticut, said.
A similar version of the plan passed the US House of Representatives on Wednesday night by 237-170, but the senate must also pass the deal before George Bush, the US president, can sign it into law.
Earlier on Thursday, Republicans appeared to have strengthened their opposition to a proposed $14 billion bailout for ailing US car makers despite pleas from the White House and Barack Obama, the US president-elect, to pass the measure.
Mitch McConnell, Republican senate minority leader, said on Thursday he opposed the measure - developed by the White House and congressional Democrats, because it "wasn't nearly tough enough".
In Chicago, Obama said the US government could not leave the industry to collapse, saying it would have a "devastating ripple effect" throughout the US economy.
Dana Perino, the White House spokeswoman, echoed Obama's statement, saying the meltdown of the car industry was "something our economy can't withstand at the moment".
|Car manufacturer executives say their firms will collapse if no bailout is passed [Reuters]
"We believe that the economy is in such a weakened state right now that adding another possible loss of one million jobs is just something our economy cannot sustain at the moment," she said.
Ford, Chrysler and General Motors, have spent weeks pleading with US politicians to assist their ailing firms, saying their collapse could devastate the economy and cause millions of job losses.
All have been criticised for failing to restructure and adapt to the market by providing more fuel-efficient vehicles.
Rob Reynolds, Al Jazeera's Washington correspondent, said some Republicans were being open about their desire to see trade unions take a "big hit" on the issue.
GM and Chrysler are seeking billions of dollars by the end of the month just to survive while Ford is asking for a line of credit if its finances worsen more than expected in 2009.
Under the proposed bailout terms - which could be amended to pass the bill through the senate - the loans are intended to assist the firms until the end of March 2009, after which future help would depend on the quality of restructuring plans demonstrating their viability.
A presidentially appointed trustee, or "car czar" would enforce the loan conditions and judge the restructuring plans and could recommend bankruptcy if he or she deemed the companies' plans to be insufficient.