(Adds CBO estimates of cost)
By Eric Beech
WASHINGTON, Jan 28 (Reuters) - Leaders of the House and Senate agriculture committees are optimistic that the long-overdue U.S. farm bill will pass, although the House of Representatives vote set for Wednesday could be the more difficult hurdle.
House Agriculture Committee Chairman Frank Lucas said on a conference call with reporters on Tuesday that there are a number of House members - both liberal and conservative - who are opposed to sprawling legislation unveiled on Monday by congressional negotiators.
"I've always known that the folks at both ends of the spectrum would not support us," said Lucas, an Oklahoma Republican. "It's the coalition of the folks in the middle who want to get things done ... who will pass this bill."
"If it was easy, it wouldn't be the farm bill," he added.
Lucas said liberal members objected to cuts of about 1 percent a year in funding for the Supplemental Nutrition Assistance Program (SNAP), commonly known as food stamps, which provides assistance for low-income Americans to buy food.
The cut was double what was proposed in the farm bill passed last year by the Democratic-led Senate.
At the same time, many conservatives thought the savings in the overall bill, an estimated $23 billion to $24 billion compared with current funding, wasn't enough.
Separately, a report by the Congressional Budget Office on Tuesday estimated that farm bill savings would total $16.6 billion over the 10 years starting in 2014 - less than lawmakers had contended.
Conservative pressure groups Heritage Action and Club for Growth urged a "no" vote on the bill on Tuesday and said they would include the results in their scorecards of members' voting records for 2014.
House members on Tuesday took a procedural vote that clears the way for a farm bill debate and final vote on Wednesday.
Senate Agriculture Committee Chairwoman Debbie Stabenow sounded more confident about the vote in the Democrat-run Senate, which could come as early as next week. There is a "strong bipartisan coalition" supporting the bill, she said.
Both Lucas and Stabenow said they had "every indication" from the White House that President Barack Obama would sign the bill.
KEEPING MEAT "COOL"
Monday's agreement on the legislation came after lawmakers spent months ironing out differences over food stamps, crop insurance, farm subsidies and other issues contained in earlier House and Senate legislation.
Although farm bills are written every five years, the CBO considered the 10-year costs of the legislation, which it said would total $956 billion. Of that, $756 billion could be for nutrition programs including SNAP.
Much of the modest savings identified by the CBO would come from an end to so-called direct payment subsidies, which for years have been made to farmers and landowners regardless of need.
Those payments would disappear from 2015, saving some $4.5 billion a year. But the savings are largely offset by spending on various forms of crop insurance coverage.
Despite last-minute lobbying from the meat industry, so-called country of origin labeling (COOL) remained in the bill. The provision requires meat to be labeled as to where animals are born, grown and processed.
COOL backers, including consumer groups and ranchers, say consumers have a right to know where their meat originates. U.S. meatpackers say the law imposes unnecessary costs on the industry and violates free trade provisions.
"The votes were not there" in either the House or Senate to repeal COOL, Stabenow said.
Lucas said removing the labeling law could have endangered agreement on the full bill.
Another contentious issue put to rest on Monday was an amendment from Republican Representative Steve King of Iowa that was intended to block a California law requiring that all eggs sold in the state come from chickens kept in non-confining cages.
The King amendment passed in the House, but Stabenow said it was dropped from the final bill in light of "overwhelming opposition" among the House-Senate negotiators.
Animal welfare advocates, state legislators and others had decried the amendment.
King said California violated the interstate commerce clause of the Constitution. Opponents said it could have broader consequences beyond California and invalidate hundreds of state laws on animal protection and food safety.
U.S. Agriculture Secretary Tom Vilsack said in November that the amendment "would create legal challenges and confusion in the marketplace."
Several large U.S. farm groups urged swift passage of the legislation.
"This bill provides funding for important programs in conservation, research and trade that help keep America's wheat industry productive and competitive on a global scale," said Bing Von Bergen, a wheat farmer from Moccasin, Montana, who is president of the National Association of Wheat Growers. (Reporting by Eric Beech; Editing by Ros Krasny, Jan Paschal and Leslie Adler)