President Barack Obama's hopes of overhauling the US health care system were given a major boost Thursday as two advocacy groups representing doctors and seniors backed the reforms.

The American Medical Association (AMA) and AARP both issued statements in support of health legislation currently before the House of Representatives, which could vote on the measure Saturday.

Both groups had been withholding their support amid a divisive debate among politicians that has taken up much of Obama's first year in office.

Democrats, who control both houses of Congress, are pushing for reforms aimed at cutting costs and extending coverage to about 30 million people that lack health insurance. Republicans are strongly opposed, arguing the proposals amount to a government-takeover of the largely private system.

Obama, who made health reform his top domestic priority and wants it passed by the end of the year, said he was 'extraordinarily pleased' with the latest endorsements.

'We are closer to passing this reform than ever before,' said Obama, who made a surprise appearance at the White House's daily press briefing.

The backing could inject fresh momentum into what has been a long-running battle in Congress. The House could pass its version of the bill, which includes a controversial government-run insurance option, on Saturday.

The House vote will be strictly along party lines. The Senate has yet to decide when to begin debating its own version of the legislation. If passed, the two bills would then have to be reconciled before they can reach Obama's desk.

AMA President James Rohack said the House bill was 'consistent with our principles of pluralism, freedom of choice, freedom of physician practice and universal access.' The AMA represents doctors and nurses around the country.

Barry Rand, chief executive of AARP, the leading advocacy group for senior citizens, said the bill met the organization's 'twin goals of making coverage affordable to our younger members and protecting Medicare,' an existing government-run insurance option for seniors.