A Republican congressman from a heavily Hispanic district is breaking ranks from his party to join Democrats in an eleventh-hour push for a broad immigration overhaul before the end of the year.

Rep. Jeff Denham from California plans to sign on as the lone GOP member with 185 Democrats to cosponsor a plan that will give millions of unauthorized immigrants the chance to attain citizenship.

A handful of House Republicans have expressed support for citizenship legislation similar to the bipartisan bill that passed the Senate over the summer. But Denham is taking the additional — and politically provocative — step of locking arms with House Minority Leader Nancy Pelosi, also from California, and other top Democrats trying to neutralize opposition from House conservatives and shake up a polarized immigration debate.

"I'm the first Republican," he said in an interview. "I expect more to come on board."