WASHINGTON — With the votes lined up, the Senate Tuesday was poised to set in motion the final countdown to a vote on financial regulatory reform.

The chamber could pass the final legislation as soon as Thursday. It would then go to President Obama, who is expected to sign the sweeping bill into law soon.

The final vote needed for the legislation fell into place Tuesday. Sen. Ben Nelson, a Nebraska Democrat who signaled he might have concerns and remained undecided as late as Monday, said Tuesday that he would support the legislation. His promised vote came on the heels of two other critical vote confirmations, with Republican Sens. Scott Brown of Massachusetts and Olympia Snowe of Maine saying Monday that they would vote in favor of the regulatory overhaul.

That means that barring any unforeseen upheavals, Democrats have the assurances they need to secure the 60 votes needed for Senate passage of the bill regardless of the pending appointment to the West Virginia Senate seat. (The seat became vacant with the death of Democrat Sen. Robert C. Byrd and is expected to be filled by the governor with a temporary appointment by next week.)

"Nebraska taxpayers have already been asked to bail out banks and now we must protect them from future abuses by Wall Street that cost thousands of Nebraskans and millions of Americans their jobs, savings and financial security," Nelson said in a press release Tuesday announcing his support for the bill. "I will support the Wall Street reform bill to end bailouts, add common-sense consumer protections and make sure that Nebraska Main Street businesses are not adversely affected as we rein in recklessness on Wall Street."

Senate Majority Leader Harry Reid said the Senate would start its final work Tuesday on the financial reform bill by filing a vote for cloture and in the meantime would continue to debate the small-business lending bill.

"We will soon finish Wall Street reform. I'm grateful that a few brave Republicans are doing the right thing for our country, but it is still disappointing that you can count on one hand the number of Republicans willing to fix the system that caused the recession," Reid told reporters Tuesday.

"Wall Street reform and unemployment assistance are two approaches to the same problem — our No. 1 priority, and that's jobs. Everyone knows that the greed on Wall Street caused the problems we are having with our financial problems around the country."

Filing cloture is a procedural maneuver in the Senate that requires 60 votes to prevent a filibuster on a controversial bill. The motion takes a few days to "ripen," and would set the clock for a procedural vote Thursday.

If the cloture motion achieves 60 votes as anticipated, final passage on the bill would require only a simple majority and could easily be achieved quickly after the cloture vote.

Reid, however, acknowledged Tuesday that Republicans could insist on debating the bill for 30 hours and delay final passage to Saturday.

"I hope to have a vote on it Thursday morning," he said. "I'm hopeful and confident that we'll get cloture on that and I hope that the Republicans won't take the 30 hours — if they do we'll have to come back to finish it on Saturday, but we are going to finish the bill."

Reid also said he hoped the Senate would soon complete a bill that would establish a $30 billion small-business lending fund but said Republicans were throwing up roadblocks by arguing over amendments to the bill.

"On the small-business bill, we are doing our best to work through that," Reid said. "We are not getting a lot of help from our Republican friends. We've told them that this is a bill that there should be amendments offered. … The bill that we put on the floor is a pretty good bill standing alone."

Observers said Tuesday that the Senate's vote on regulatory reform is mostly a procedural formality at this stage and predicted that the bill would move quickly with the votes apparently locked down.

"As soon as they have the 60 votes lined up, they will move it forward to the Senate floor," said Joseph Engelhard, a senior vice president with Capital Alpha Partners. "I wouldn't be surprised to see it up for a vote as soon as Thursday.

After an often contentious and drawn-out House-Senate conference to hammer out the final bill, the House adopted the conference report last month. That means the Senate vote is the last step needed.

Sen. Jeff Merkley, a Democrat from Oregon who was instrumental in strengthening the bill's ban on proprietary trading, known as the Volcker Rule, said he was confident that the bill would be sent to the president soon. He said he thinks it might pick up the votes of more Senate Republicans.

"It feels like we are on the homestretch. I look forward to getting it sent off to the president's desk," Merkley said in a brief interview Tuesday.

"It will be interesting to see what the vote is post-cloture," Merkley continued. "I still believe that there may be a number of my colleagues across the aisle who recognize that reforming retail mortgages, getting rid of tricks and traps and financial scams, and reducing systemic risk on Wall Street are the right thing to do for America, so I wouldn't be surprised if we have a bunch of people come over at the last minute."

Senate Banking Committee Chairman Chris Dodd, the architect of the bill in the Senate, was guarded in his outlook.

"I'm never confident," the Connecticut Democrat, who is retiring at the end of this session, told reporters. "I always want to see the votes counted. I've been around too long to be confident."

Dodd had to take the rare step of reconvening the conference committee last month to take out a proposed tax on large institutions to offset the cost of the bill after key Republicans threatened to oppose the bill.

"I'm very grateful as I said to all of my colleagues who have been helpful on the bill — some substantively, but others substantively and helping us get the votes. … We listened to them carefully and I am very appreciative of their support. It means a lot."

But Sen. Carl Levin, D-Mich., chairman of the Permanent Subcommittee on Investigations, said he was already focused on the next step, holding oversight hearings to ensure that regulators are appropriately implementing the bill and continuing to investigate financial institutions.

"I think we need to have — assuming the bill's passed — some very strong, ongoing and constant oversight," Levin said. "It is also necessary that that be done for the regulations. … As soon as the bill is signed, we ought to look at a process for oversight."