Not passing the bill could put a crimp in the plan for Democrats over the August break to sell themselves as supporting small businesses while painting Republicans as being in the pocket of big business executives and Wall Street.
Durbin said the refusal by Sen. Olympia Snowe (R-Maine) to support the bill is the primary reason why it might not pass before the break.
"Sen. Snowe has concerns with one provision," he said. "You ought to talk to her about it."
John Gentzel, Snowe's communications director, told The Hill that his boss is not holding up the bill, but has been trying for months to move the legislation forward.
"Unfortunately, we've wasted the whole week trying to get amendments pending but the tree has been filled, prohibiting an open amendment process," he said. "Leader McConnell clearly stated yesterday that the Republicans hope to move forward with some amendments and pass a much needed small business bill. But we are still waiting for the majority to accept amendments to consider. For her part, Senator Snowe is working together with leadership, on both sides of the aisle, and other key senators in an effort to forge a package that can pass the Senate."
The legislation creates a $30 billion lending pool and provides approximately $12 billion in tax relief to small businesses.
One of its tax breaks allows the self-employed to claim health insurance costs as a business deduction, which sole-proprietors have sought ever since health care costs began outpacing inflation.
The small business bill has had a rocky life in the Senate. Senate Majority Leader Harry Reid (D-Nev.) has pulled it from the floor twice to deal with more pressing issues and the dispute over amendments has yet to abate.
Republicans would like to add a permanent estate tax fix to the legislation that was offered on Wednesday by Sens. Jon Kyl (R-Ariz.) and Blanche Lincoln (D-Ark.). Reid apparently does not think the bill is the best place for it, much to Kyl's chagrin.
"If the Small Business Lending bill is intended to help small business create jobs, wouldn't it make sense to provide small-business owners with the certainty that their tax rates aren't going to skyrocket at the beginning of next year?" Kyl said in prepared remarks when he and Lincoln introduced their bill.
Sen. Claire McCaskill (D-Mo.) surmises that Reid knows the Kyl-Lincoln proposal is popular and wants to use it as a vehicle for moving other initiatives instead of attaching it to the small business bill.
"It's the one thing that Republicans will be willing to vote on," she told The Hill. "So I think the leader is trying to figure out what else could ride on that train with it, in terms of forcing a vote on things."