House Majority Leader Kevin McCarthy is facing a long-shot campaign challenge from a Mexican-born farmworker.

Raul Garcia, who says he became a naturalized citizen after immigrating to this country illegally, got on the ballot as a write-in candidate thanks to a quirk in California's primary election system.

Now he has union backing and ambitions to put McCarthy on the spot in his own agriculture-rich backyard for the failure of the Republican House to move immigration legislation.

In a new campaign ad Garcia asks McCarthy a provocative question: "While we are waiting for you on immigration reform, who should be harvesting America's food?"

McCarthy says in a statement that he will keep working hard for the district, but he had no comment on Garcia's candidacy.