President Barack Obama's latest attempt at a bipartisan deal for health care reform has fallen flat, with liberal Democrats displeased about a retreat from a "government option" and Republicans showing little interest in working across the aisle.

On the weekend, Obama and his top aides seemed to suggest they were backing off a key provision to have health care insurance run by the government to compete with private insurers.

"All I'm saying is, though, that the public option, whether we have it or we don't have it, is not the entirety of health care reform," the president told a town hall in Colorado on Saturday. "This is just one sliver of it, one aspect of it."

The comment set off Howard Dean, a former Democratic chairman who hails from the more liberal wing of the party.

"You really can't do health reform" with a government health plan to compete with private plans, he said. "Let's not say we're doing health reform without a public option."

Analysts suggest that Obama, in his effort to secure the 60 votes needed in the Senate, is in danger of losing support from the Democratic-led House of Representatives. There are 256 Democrats in the House, and 218 votes are needed to pass a bill.

Already more than 50 Democratic members of the House have said they won't support a more conservative health care bill.

House Leader Nancy Pelosi issued a statement Monday saying she's strongly behind a public option, but didn't go so far as to say she wouldn't support a health care bill without one.

"As the President stated in March, 'The thinking on the public option has been that it gives consumers more choices and it helps keep the private sector honest, because there's some competition out there,'" the statement said.

"A public option is the best option to lower costs, improve the quality of health care, ensure choice and expand coverage."

The other alternative on the table for Democrats is the so-called "Co-op" option - proposals for the creation of non-profit ventures for health care. However, while some centrists prefer the plan, neither Republicans nor most Democrats have shown much support.

The health care reform issue has become a political minefield in Washington, with the public option being the most contentious factor.

Recent polls have shown support for Obama and the Democrats weakening, especially on the health care file, and raucous protests have sprung up across the U.S.

On Monday, at least three men were seen openly carrying weapons at a protest for Obama's appearance in Phoenix. While it is legal to openly brandish a firearm in Arizona, the rise in the number of death threats against the president makes the situation unsettling to many.

While there is a six-person bipartisan committee working in the Senate on healthcare, little support is expected from Republicans for Obama.

The Senate Republican leader, Mitch McConnell, issued a statement Monday criticizing Obama's plans.

"While both political parties believe we need to reform our health care system, particularly in the areas of cost and access, Americans are rightly skeptical about the administration's approach to overhauling everyone's health care and about the more than $1 trillion price tag. Moreover, Americans are concerned about funding new government programs through massive cuts to Medicare and taxes on small business," he said.