Washington, Mar 19 (DPA): US President Barack Obama has been forced to postpone until June a trip to Asia, as his fellow Democrats scrambled for support Thursday ahead of a final vote on health care reform as early as this weekend in the House of Representatives.

Obama had been set to leave Sunday on a trip to Indonesia and Australia after already delaying his departure by a few days. Spokesman Robert Gibbs cited the critical health care vote in the House as the chief reason for the president's decision to remain in Washington.

Obama "greatly regrets" the trip's delay, Gibbs said, but "passage of health insurance reform is of paramount importance, and the president is determined to see this battle through".

Health care reform has been Obama's top domestic priority and engulfed much of his presidency since entering office in January 2009. With the finishing line in sight, Obama was busy making last-minute calls and hosting wavering lawmakers throughout this week.

The House Democratic leadership Thursday posted the entire legislation online. The chamber's rules require the public to be able to review a bill for at least 72 hours before it can be voted on. That would allow a final vote Sunday afternoon at the earliest.

A weekend vote would be extremely close, despite the Democratic Party's strong majority in the chamber, and could yet be pushed into next week. Obama faced strong pressure from his centre-left party's lawmakers to cancel his Asia trip and personally help make the final pitch for reform.

Obama had already delayed the trip to Asia by three days, but with lawmakers wavering in the last week over when the health vote would take place, Gibbs said it "seemed obvious to us that the best course of business was to reschedule Indonesia and Australia to June".

The health reforms in Congress are considered the most comprehensive since the 1960s and a make-or-break moment for Obama's young presidency. The overhaul is designed to extend coverage to about 30 million Americans who lack insurance and help reduce costs in a health sector that consumes about 17 percent of the US economy.

Centre-right Republicans are united in opposition to the reforms, and some moderate Democrats have refused to back the legislation because of its steep price tag and increased government involvement in what is a largely private system.

A small group of conservative Democrats also oppose the bill over language that could leave open the possibility of federal funding for abortions.

Approval of the bill Sunday by the House of Representatives would set up a final vote by the Senate, possibly in the coming week. Both chambers passed differing versions of the health bill late last year but must vote again on changes that reconcile their two versions.

Obama earlier Thursday touted new figures from the Congressional Budget Office (CBO), a non-partisan arbiter of legislative costs, which found the reforms would cost $940 billion over 10 years but would reduce the federal budget deficit by $130 billion over that period. The costs would be offset by a tax on expensive health plans and streamlining an existing government insurance plan for seniors.

"This is but one virtue of a reform that will bring new accountability to the insurance industry and economic security to all Americans," Obama said at the White House.