At least four or five Republicans will break rank with the GOP to support Democrats' Wall Street reform bill, Sen. Bob Corker (R-Tenn.) said Tuesday.

Corker, a key negotiator on the bill to overhaul U.S. financial regulations, said he would not be among those Republicans to support the overall legislation, which has been the subject of debate and numerous amendments in the Senate this month.

"I think that we know that there are probably at least five Republicans who are going to vote for this bill," Corker said during an appearance on CNBC. "I think we've seen that in the voting patterns."

Senate Majority Leader Harry Reid (D-Nev.) filed cloture on the bill on Monday evening, setting up a key procedural vote for Wednesday, and a vote on passing the bill as a whole as soon as Thursday.

Republicans like Corker and Sen. Richard Shelby (R-Ala.), the ranking member of the Senate Banking Committee, have long negotiated with Democrats over the content of the bill, though an agreement has continued to escape Democrats and Republicans on the legislation.

Some GOP amendments to the bill have been added over the past few weeks, though many Republicans have maintained reservations about the new regulations.

Corker said he's not sure what motivates his colleagues to support the legislation. If all 41 Republican senators stuck together, they could block the bill from going forward.

"They may think this is an awesome bill," he said. "I'm one senator, and I'm not particularly thrilled with the policy, as you well know."

Senators like Susan Collins (R-Maine) and Richard Lugar (R-Ind.), among other GOP lawmakers, have occasionally broken with their party throughout the voting process on amendments, leading to speculation that they might support the bill on final passage.

"We've got about four or five Republicans that, I think, are going to vote for this," Corker said at another point in the interview.