WASHINGTON — The House Agriculture Committee encountered an ideological rift today over the federal food stamp program as it began voting on a half-trillion-dollar farm policy and food assistance bill.

The panel was caught between Republicans, clamoring for cuts to a program that has doubled in costs during the past four years, and Democrats who contend any cuts to the $80 billion-a-year food stamp program will result in people going hungry.

The panel was expected to work deep into today and possibly into Thursday to consider dozens of amendments on other areas as varied as crop insurance subsidies and government support for sugar and milk producers.

The Senate passed its version of the five-year farm bill on a bipartisan vote last month. The future is less certain in the House, where GOP leaders have not committed to bringing the legislation to the floor once it emerges from the Agriculture Committee.