Members of the Senate’s Gang of Eight say they are open to amending the 844-page immigration reform bill they unveiled this week but will band together to defeat poison-pill amendments.

“We expect and welcome suggested improvements to the bill by our colleagues,” Sen. John McCain (R-Ariz.) said at a press conference Thursday. “We will oppose only those amendments that are intended to prevent a comprehensive solution from passing.”

Business groups want to increase the number of visas for immigrant workers while labor unions want to speed up the path to citizenship for an estimated 11 million illegal immigrants.