WASHINGTON — Congress' efforts to overhaul the nation's health care system are plagued by an age-old urban-rural, east and west coast vs. the heartland schism in the Democratic Party.

The divide is constantly evident. Last week, for instance, Rep. Pete Stark, D-Calif., chairman of the House Ways and Means Health Subcommittee, offered a glimpse of the tension when asked about health care co-ops.

"Well, the only co-op I know about is when I used to milk cows and we sold the milk to Golden Guernsey. And I think there's only one co-op left," said Stark, who considers the co-op idea a non-starter. "There aren't many of you listening who remember the co-ops of the '30s, which was a — just kind of a Roosevelt outgrowth of rural electric co-ops, phone co-ops."

The same day, Rep. Charlie Melancon, D-La., a leader of the conservative House of Representatives Democratic Blue Dog Coalition, announced he was running for the U.S. Senate.

He promised a "more bipartisan, more disciplined" approach, and touted himself as a "pro-life, pro-gun Southern Democrat."

Stark and Melancon are typical of the party's division. "The two sides don't understand each other. They're reading from different scripts," said Steven Schier, professor of political science at Carleton College in Northfield, Minn.

Not everyone agreed that the differences would stymie health care this year. Ron Pollack, the executive director of Families USA, a consumer health organization, noted that lawmakers agree on many major health care changes.

The divisions, however, already have affected the issue that appears likely to make or break the progress of health care changes — whether to adopt a "public option" insurance choice or endorse creation of co-ops to help make the health care system more efficient.

The co-ops would be non-profit organizations that would run themselves. Members and an elected board would make decisions about premiums, benefits, deductibles and co-pays.

While the details of how they'd work remain sketchy, under consideration is a plan that would have co-ops contract directly with health care providers. They could negotiate rates with a network of approved physicians and hospitals. Some cooperatives would have their own doctors as well as hospitals.

"People here understand the public option, but they don't really know what co-ops are," said Gary Rose, a government and politics professor at Sacred Heart University in Fairfield, Conn.

The co-op idea is getting serious consideration from negotiators at the Senate Finance Committee, all of whom come from smaller, less urban states. The chief backer is Sen. Kent Conrad, D-N.D.

"It has appeal on both sides," he said. "It's the only proposal that has bipartisan support."

The idea of co-ops has been met by derision and outright hostility in Congress, however.

"It's a way to avoid and a way to silence what I consider to be a pretty strong drumbeat for a public option in the country," said Rep. Raul Grijalva, D-Ariz.

The public option idea has been endorsed by Democrats on committees led by Reps. Henry Waxman of Los Angeles, George Miller, who represents the San Francisco Bay area, and Christopher Dodd, a Connecticut senator.

Generally, their plans would have consumers shop for coverage, and be able to compare private and public plans. Total cost of legislation endorsed by three House committees and Dodd's panel is estimated at about $1 trillion. The panels hope to offset the costs by implementing cost savings and increasing some taxes.