Washington, Dec 23 - US President Barack Obama has vowed to remain in Washington until the health care reform bill wins Senate approval, effectively pushing back the departure date for his holiday vacation in Hawaii.

"I will not leave until my friends in the Senate have completed their work," Obama said.

"My attitude is, is that if they're making these sacrifices to provide health care to all Americans, then the least I can do is to be around and to provide them any encouragement and last-minute help if necessary," he said.

Obama was scheduled to fly out Wednesday, but it appears the Senate won't hold a final vote on the health care legislation until at least Thursday morning - Christmas Eve.

The Senate has been in late night and weekend sessions as it tries to wrap up business before the year ends, mostly focusing on a legislation that would overhaul the health care system and extend medical coverage to uninsured Americans.

This is the longest Senate session in years, and the first time since 1963 it has met on Christmas Eve, according to the Washington Post.

Reforming health care has been among Obama's top priorities since he took office, and he appears close to the historic achievement that would mark the most significant change to the health system in decades.

The Senate bill nudged closer to passage earlier Tuesday when Democrats mustered the 60 votes needed in a key test vote. There will be one more vote to end debate in the next day before the final, simple majority vote.

Republicans have united in opposing the bill, arguing it will turn into a costly enlargement of the federal government. The bill would extend medical coverage to 30 million Americans without insurance. Democrats, along with two independents, control 60 of the 100 Senate seats.

The House of Representatives passed their version in November. Once the Senate measure passes, both chambers will have to work out differences in their respective bills before Obama can sign it into law, which could take place early next year. (dpa)