Senate Democrats face uncertainty in their Wednesday afternoon vote to close debate on a financial overhaul because of potential defections from disaffected members of their own party.

Several Democratic sources said getting the 60 votes needed to beat back an attempted filibuster, or invoke cloture, could fall short at the 2 p.m. vote because several Democrats are angry that they have not been able to get votes on their amendments.

However, Democratic leaders are still relatively optimistic that they will be able to persuade intransigent Members to fall in line before the vote is held, aides and Senators said.

On Wednesday morning, several Democratic Senators loitered on the floor as they attempted to secure a last-minute vote on their proposals. Sen. Sheldon Whitehouse (D-R.I.) vowed on the floor to press his amendment and was seen huddling with the parliamentarian in an attempt to prevent his proposal to allow states to regulate credit card rates marketed in their jurisdiction from being declared nongermane after cloture has been invoked.

Asked whether he would support ending debate Wednesday, Sen. Tom Harkin (D-Iowa) — who wants a vote on his ATM fee amendment — said, “Well, we’ll see,” as he headed to the floor Wednesday morning.

Similarly, Sen. Byron Dorgan (D-N.D.) waited on the floor and strategized with other Democrats on how to get a vote on his amendment to ban “naked swaps.” Senate Banking Chairman Chris Dodd (D-Conn.) huddled with Sen. Maria Cantwell (D-Wash.), who was hoping to get a vote on her amendment with Sen. John McCain (R-Ariz.) to reimpose Depression-era restrictions on banks, insurance companies and securities firms. However, McCain said he doubted the proposal would come up for a vote.

Sens. Carl Levin (D-Mich.) and Jeff Merkley (D-Ore.) also were seen on the floor talking as they waited to see whether their plan to ban banks from proprietary derivatives trading would come up.

Both Dodd and Majority Whip Dick Durbin (D-Ill.) were on the floor talking to wavering Democrats.

Though Democratic leaders are blaming the inability to hold votes on a variety of amendments on the unwillingness of Republicans to agree, many Democrats also blame Dodd and the White House for opposing their proposals and delaying their ability to get a vote before Wednesday. Whitehouse, for example, wanted to offer his amendment during last year’s Senate debate on a credit card consumer protection bill, but Dodd asked him to withhold it.

Even as Democrats held out the possibility that they might filibuster their own financial reform bill, Republicans began to come forward to say they would support an end to debate. Sen. Susan Collins (R-Maine) announced Wednesday morning that she would support cloture, for example.

But the number of Republicans expected to vote with Democratic leaders may not be enough to offset the Democratic defections, sources cautioned.