CHICAGO  More than two weeks after Wisconsin lawmakers split over a bill that would vastly curtail collective bargaining for public workers, even negotiations over the negotiations have become matters of division, fury and dueling public critiques.

Scott Fitzgerald, the Republican leader in Wisconsin’s Senate, described the progress of talks with 14 Senate Democrats who left the state last month to block a vote on the bill as “negotiating with Jell-O.” And in a letter about the talks to his Democratic counterpart, Mr. Fitzgerald questioned his colleague’s “grasp of reality.”

Chris Larson, one of the Senate Democrats, accused Mr. Fitzgerald and Gov. Scott Walker, the Republican who proposed the measure, of misleading the public, trying to shift blame to the Democrats, and “throwing people who were negotiating in earnest under the bus.”