MONTPELIER – U.S. Sen. Bernard Sanders drew a line in the sand on health care reform this weekend, saying he will not vote for a bill that does not include a public health insurance option.

The independent Vermont senator, who supports a more expansive single-payer health care system, said Monday afternoon that there are a "number of problems" with the Senate bill, including that it contains a weak public option.

Sanders did vote to begin debate on the bill Saturday night, giving Democrats the much needed 60 votes to overcome a Republican filibuster and send the 10-year, $959 billion health bill to full debate.

But he said his vote for the underlying bill is not yet secure.

"The American people overwhelmingly support a public option," Sanders said. "Democrats in the House and President Obama support a public option. And a majority of Democrats in the Senate support a public option."

Despite that support, the likelihood that a Senate bill containing such a public option – an insurance plan administered by the federal government that would compete against private plans – is unclear, with moderate and conservative Democrats saying they would not support it.

Sanders said the United States got into this crisis because President Bush did very little to reform health care or curb costs during his eight years in office.

"The American people want a public option that would compete against the private insurance companies, whose only goal in life is to make as much money as possible," Sanders said. "If we do nothing, the dollars we spend on health care will nearly double in the next eight years."

The House passed its health care bill 220-215 earlier this month. The Senate vote cleared the way for debate on a bill that is a compromise between two committee-passed versions and could undergo significant changes as senators amend it during weeks of arduous debate ahead. There are significant differences among congressional Democrats over abortion and taxes as well as letting the government sell health insurance as a competitor with private insurers.

Former Vermont Gov. Howard Dean, who chaired the Democratic National Committee for two terms after leaving office, warned in an interview with the Huffington Post on Monday that Democrats are in "deep trouble" even if they pass a strong reform bill.

"I think if you passed the Senate bill tomorrow it would be OK," Dean told the Web site. "But then the problem is they don't have any defense for their members in 2010. On the other hand, if they drop the public option, I think they lose seats."

U.S. Sen. Patrick Leahy, D-Vt., spoke on the Senate floor encouraging a vote on the bill.

"Vote no if you want on the final bill but at least let's have a debate and vote on it," Leahy said. "When we get a final bill we will either vote for it or against it."

Leahy said leaders in the Senate have told him there will be work done to correct Medicaid language that could disadvantage Vermont, which has gone farther than other states on its own health care reform efforts.

"I have been assured and was assured over the weekend we would fix Vermont's Medicaid problem," Leahy said. "I want to see the final wording, of course"

With the U.S. Congress on break this week for Thanksgiving, Sanders anticipates debate to begin in early December when lawmakers return to Washington, D.C. Debate could continue for several weeks and even stretch into 2010, he added.

"I can see this debate progressing over the next three to four weeks," he said. "Right now, we have four people in my office exclusively working on this bill."

Sanders said there are provisions in the bill that he likes, including ones that would give 31 million more Americans health insurance, allow young people to stay on their parent's coverage for longer and prohibit insurance companies from denying or dropping coverage due to a preexisting condition or a health crisis.

But there are problems as well, he said. The House version of the bill paid for expanded coverage by taxing the country's wealthy. The Senate version, however, taxes what Sanders calls "Cadillac" health plans, but he worries that today's good car could be tomorrow's clunker.

The Senate version of the health care bill also lacks funding right now for one of Sanders' pet issues: Expanding community health centers across the country. The House version contained expansive language and funding, but the Senate's bill does not fund that effort yet.

Sanders said Vermont – which has been very progressive compared to other states in reforming health care – should not be penalized for having Dr. Dynasaur and a generous Medicare program. He said he will fight to include language in the final bill that will give states such as Vermont "flexibility" to try other health care systems, including a single-payer system.