Reid's warning came as he set up a procedural vote on the Food and Drug Administration Safety and Innovation Act (S. 3187) for 11 a.m. on Wednesday. The legislation creates a user-fee system for generic and biosimilar drugs seeking FDA approval.

"On the bill I hope we can workout some finite list of amendments," Reid said Tuesday afternoon. "That would be the best thing to do for this bill. So I just say to everyone, I hope we can do that. I don't want to come here tomorrow and file cloture on the bill, but that's a choice I'll have."

Reid also said he could also move to reconsider a student loan interest rate bill that has been in limbo since the Senate rejected a procedural move to advance the bill. 

"Maybe what I might do is vote to reconsider the student loan, I have the ability to do that," Reid said. "We need to get this done."

Reid said an agreement over considering amendments to the bill had to be made by Wednesday morning.

"So we don't have a lot of time, so tomorrow morning if we don't have something worked out I think we'll have to do some other things," Reid said.