The guest-worker issue helped derail the last serious attempt at reform in 2007 with assistance from Obama, then a U.S. senator from Illinois. The current attempt at reform is being led by a bipartisan group of eight senators, who are attempting to fashion model legislation for a broad immigration overhaul.

The dispute centers on rules governing the “future flow” of migrants who come to the United States for menial jobs. Republicans, citing business interests, want to give temporary work visas to up to 400,000 foreign workers a year at low wages. But unions and many Democrats, fearing the effect on U.S. workers, want fewer workers and higher pay under the program…

Union officials think that they have leverage because they have publicly committed to supporting Obama’s push for a path to citizenship — a key issue for Hispanic voters, who overwhelmingly supported the president’s reelection last year.

“This is not what Barack Obama campaigned on,” AFL-CIO spokesman Jeff Hauser said. “I don’t understand why people believe business has a seat at the main table after fighting for anti-citizenship candidates in 2012.”