John McCain, a Republican senator, said earlier that his party would "fight the good fight ... until the last vote".

The majority of Republicans believe that the bill would mean too much government interference in the system which should be market controlled.

The Democrats secured the 60 senate votes needed to avoid Republican procedural hurdles after making concessions to Bill Nelson, a Democratic senator from Nebraska.

'Enormous compromise'

To gain his support changes were made in the language of the bill, stating that federal funds would not be used for abortions, and extra finance would be allotted for healthcare in Nelson's home state.

In video


Al Jazeera's Rosiland Jordan reports on the unpredictable outcome of the health bill

But detractors have said the bill is not strong enough to overhaul the healthcare system after a public option to extend government-backed coverage to 36 million people without insurance was dropped.

Howard Dean, a Democratic politician who has supported healthcare reform, said that the administration of Barak Obama, the president, and Democratic legislators had been too flexible in their concessions.

"I think there's been an enormous amount of compromise. I think it's been too much," he said on US television network NBC.

"We don't think there has been much fight in the White House for [a public option]."

Legislation defended

David Axelrod, Obama's senior advisor, countered that the bill still upheld the administration's goals of change and reform.

"This is a very, very strong bill. It's going to help give security to people who have insurance today, and it will help people who can't afford insurance, and small businesses who can't afford insurance, [to] get insurance," he said on CNN.

He said the bill would help prevent people with pre-existing health conditions from being denied insurance.

"That is the change the president promised. That's the change we're close to delivering," said Axelrod.

The senate bill will still have to be reconciled with a similar bill passed in the House of Representatives in November.

That bill includes stronger language on preventing funds from being used for abortion, but does include the public option.

Further debate

Both chambers of congress will then have to vote on the merged bill again before it can finally be passed to Obama.

The senate bill would see the biggest changes in the US system since the Medicare programme for elderly people was installed in the 1960s.

The bill states that most citizens should have health insurance and would provide for tens of millions of Americans to receive previously unattainable cover via subsidies.

It would also reduce other barriers to gaining insurance, with those without work-based cover being given options to buy cover and practices such as people with existing health problems being denied insurance being prevented.