A few weeks ago, I attended a four-day seminar where experts from across the political spectrum discussed the 2008 presidential candidates’ ideas for improving America’s health care system.

The experts – from foundations, think tanks, business and other interest groups – talked plenty about the failings of the current system, and about the proposals to fix it that have been floated by Hillary Rodham Clinton, Barack Obama, John Edwards, Mitt Romney, Rudy Giuliani and John McCain.

But Dennis Kucinich? Strikingly, Kucinich’s name almost never came up, even though the Cleveland Democrat has proposed what is by far the most sweeping health reform plan of any of the presidential candidates.

By the end of the program, presented by the National Press Foundation, one thing was clear: Plenty of the people who will play a role in the next big health reform debate, on the left and right, have concluded that Kucinich and his Medicare-for-all plan are irrelevant.

And that is true not only of people who represent pharmaceutical companies, health insurance companies and employers. It appears to be true also of people sympathetic to Kucinich’s longing for a national health care system that covers all Americans, as well as people who study the issue and don’t take a stand on what solution would be best.

Jennifer Tolbert, a policy analyst at the nonpartisan Kaiser Family Foundation, who provided an overview of the highlights of the major candidates’ plans, spent maybe 20 seconds on Kucinich, noting simply that he is the only candidate proposing a single-payer national health care plan.

Karen Davis, president of the Commonwealth Fund – a private foundation dedicated to finding ways of expanding and improving health care – didn’t even include Kucinich in her presentation on the opening night of the program.

When I asked Davis what she thought of Kucinich’s proposal, she said she has yet to see a realistic way of paying for such a government-run plan.

Davis is hardly a conservative on the subject. On the contrary, she said she thinks the leading Democrats aren’t going far enough in proposing changes to the current system, even though Clinton and Edwards have proposed covering all Americans, and Obama has proposed covering most.

Nor is Ron Pollack a conservative. Pollack is head of Families USA, a liberal nonprofit group that has been pressing for 25 years for expanding health coverage to the uninsured and under-insured. But he, too, quickly dismissed the possibility that a single-payer plan could get through Congress in the foreseeable future. The idea that such a plan could pass, he said, is “wholly unrealistic.”

Achieving any major expansion of health coverage will be an extraordinarily difficult political task, Pollack predicted. If it happens in 2009, he said, it will require a Democratic president who is willing to do several things: start crusading on the issue “on day one” after winning election, compromise with Republicans to avoid a fatal filibuster in the Senate and work with a range of interest groups that traditionally have fought one another.

For health care reform to succeed, he said, liberal groups like his would have to be willing to make alliances of “strange bedfellows” with groups like America’s Health Insurance Plans, which represents the health insurance companies that Kucinich often blames for much of what’s wrong with the current system.

Alas, Kucinich seemed a nonfactor even to David Himmelstein, an associate professor of medicine at Harvard who co-founded Physicians for a National Health Program – a national group of doctors that has endorsed a single-payer health care bill proposed by Michigan Democratic Rep. John Conyers and Kucinich.

Himmelstein’s entire presentation was devoted to making the case for a single-payer plan like the one Kucinich favors. And he insisted he believes that a strong, persuasive president could win support from Congress and the public for such a plan. Yet Himmelstein never mentioned Kucinich. Until finally, I asked: What about Kucinich’s plan?

“I love Dennis Kucinich,” Himmelstein said, smiling, “but he hasn’t caught fire.”