"Right now the public is not exposed at all to the opposition that unions have to guest-worker permits, which are critical to making this work, particularly in the agricultural states," Barbour said.
Unions and business leaders have agreed to a framework for immigration reform, but as of last week, the two sides appeared far apart on some of the details. The AFL-CIO and the U.S. Chamber of Commerce, whose negotiations will help shape the Senate bill, are finished with private negotiations, and are now working with the Senate group.
All of these factors made Barbour and Rendell think that reform could take longer than expected.
"At one point, when we first signed on, I was hopeful that we would lead the pack on immigration," Rendell said. "But now it looks like this is going to be a much longer and tougher slog."