Movement in the House and Senate on revising U.S. immigration law belies a long-running rift between business and labor that could derail the bill.

After four years of negotiations, a bipartisan group of House members who struck a deal on a broader immigration bill last week have given up on finding a compromise over how many temporary workers to allow into the U.S.

As another bipartisan measure advances in the Senate, a series of amendments backed by technology and construction companies and opposed by the AFL-CIO labor federation risk upsetting a delicate balance.