The Washington Post is out with a report implying the Gang of 8 is working to block amendments to final legislation, delaying the release of a reform plan:

A bipartisan Senate group on immigration legislation is attempting to craft an agreement so secure that the eight members will oppose amendments to its core provisions, an arrangement that could delay the introduction of a bill, people familiar with the negotiations said.

The senators had said they hoped to present their proposals this week, but Republican members expressed skepticism about that timetable Sunday. The group continues to negotiate issues related to new visa programs for agricultural and high-tech workers and has not reached agreement on a guest-worker program for low-skilled foreign laborers, said the individuals, who spoke on the condition of anonymity to discuss private deliberations.