Sen. Byron Dorgan (D-N.D.) said the bill still has "many moving parts" as Democratic leaders work to shore up support for the bill.
"We've got some people who think it's not big enough. Some people think it's too large," he said, adding, "[But] a lot of things happen around here in 24 hours."
Dorgan plans to support Wednesday's vote that will limit debate on the legislation.
"I'm going to vote for cloture tomorrow," he said, adding, "If I were writing something, I might write it differently, but we're facing deadlines here, and I intend to vote for cloture."
To garner more support for the bill, Democratic leaders apparently are paring back the $140 billion bill, as centrist senators in both parties remain skeptical about the legislation.
Sen. Ben Nelson (D-Neb.) reiterated his concern to reporters on Tuesday that he could not support the proposal because it adds about $108 billion to the deficit. Sen. Olympia Snowe (R-Maine) is also concerned by the bill's borrowing and recommended that Democratic leaders strike the Medicare "doc fix" from the legislation and pay for its extension with unused stimulus funds.
Sen. Robert Casey (D-Pa.) said he was willing to scale back his COBRA amendment if it meant 60 senators would support it.
"If we can pick up some more votes and some more support, I'd be willing to talk about scaling it back," he told reporters. "The key thing is to keep the period of coverage through the end of November, but maybe we could scale back on other parts of it."
Casey said reducing the tax subsidy or shortening the 15-month coverage period are possible ways to make the provision less expensive.
There is also talk of extending the "doc fix" for less than a year, but Sen. Debbie Stabenow (D-Mich.) said she would have a hard time supporting such a change.
Sen. Sheldon Whitehouse (D-R.I.) would not comment on the bill, but did say negotiations are ongoing.
"It's still a work in progress," he said.