WASHINGTON - The Senate has begun laying the groundwork for a half-trillion-dollar farm and food bill that would end unconditional subsidies to farmers, but House Republicans' resolve to cut its biggest component - food stamps - by $13 billion a year dims its prospects of passing Congress.

The current five-year farm bill expires at the end of September, and the Senate Agriculture Committee on Friday released a draft of its plan to redesign safety nets that help farmers weather bad times while achieving $23 billion in deficit reduction. The full committee is to vote this week on the plan, which consolidates conservation programs and takes several steps, such as stopping lottery winners from getting assistance, to make the food stamp program more accountable. Of that $23 billion in savings projected over next 10 years, $4 billion comes from food stamps.

But before getting a bill to the president, lawmakers must satisfy multiple constituents with different agendas - Northern corn growers, Southern cotton farmers, insurance companies, banks, nutrition groups, and environmentalists. Most difficult will be narrowing the gap between the Democratic Senate and House Republicans taking aim at the food stamp program that comprises about 80 percent of the bill's spending.