Public support for President Barack Obama's strategy to overhaul the U.S. healthcare system appeared to waver as Republicans stepped up attacks on Monday on a plan they say is costly and unworkable.

Republican National Committee chairman Michael Steele called Obama's efforts to push healthcare legislation through Congress before the August recess a reckless experiment.

The president is rushing this experiment through Congress so fast, so soon, that we haven't had a moment to think if it would work -- or worse, to think about the consequences to our nation, our economy and our families' economic future if it doesn't, he said at the National Press Club.

Obama was to campaign for the $1 trillion plan at a local children's hospital, then in a round of television interviews and on the Internet as his administration tries to build momentum for congressional passage in two to three weeks.

His administration has struggled to overcome concerns among fiscally conservative Democrats that already burdened federal and state governments could not afford to expand healthcare for the estimated 46 million uninsured.

Last week, nonpartisan congressional budget analysts said the plan would add $239 billion to the budget deficit over 10 years, casting doubt on Obama's pledge to keep the plan within the budget.

Reforming the $2.5 trillion U.S. healthcare industry is Obama's signature domestic priority and a major test of his presidency, but he is running out of time to get the enabling legislation passed this year.

A delay to 2010, a congressional election year, could make it harder to win a final deal.

A Washington Post/ABC News poll conducted last week found approval of his handling of the issue fell to 49 percent from 57 percent in April, and disapproval rose to 44 percent from 29 percent.

But support for the plan moving through Congress was strong among his own Democrats, with 75 percent backing it, as opposed to the more than 75 percent of Republicans who opposed it.

The House Energy and Commerce Committee was to complete work on its portions of the legislation, the last of three House of Representatives committees needed to agree to the plan.

But House Democratic leaders struggled to find ways to bring the plan within the budget, as did the Senate Finance Committee, which was to continue closed-door discussions on Monday evening.

Obama repeated on Saturday he would not sign on to any health plan that adds to our deficits over the next decade.

He called on lawmakers, including skeptics in his own party, to seize this opportunity -- one we might not have again for generations -- and finally pass health insurance reform this year, in 2009.

His budget director Peter Orszag said on Sunday there were a number of options to curb the cost of the bill to keep it from increasing the federal deficit.

Remember, none of this is easy. There's a reason why this hasn't happened in 50 years, and we're making a lot of progress, Orszag said on CNN.

ROUNDING UP SUPPORTERS

Unlike President Bill Clinton's failed attempt to overhaul healthcare in the 1990s, this time around the effort is finding important supporters.

The American Medical Association announced its backing last week; pharmaceutical companies joined hands with Families USA, the chief lobbying group for the insured; and on Monday the leading health insurance trade group said it would take to television and radio to seek a bipartisan plan.

If everyone's covered, we can make health care as affordable as possible. And the words 'pre-existing condition' become a thing of the past, the America's Health Insurance Plans advertisement said.

The insurers applauded reforms that would aim for universal coverage, guarantee coverage for those with pre-existing conditions who are often excluded now, and ensure continuity of care.

The plans working their way through Congress would set up a government-run health insurance plan to compete with private insurers, provide coverage to many of the 46 million uninsured and try to stem runaway medical costs.

But a decision on how to pay for it was a ways off.

The House, in its version of the bill, would pay for about $587 billion with new taxes, including one on the wealthy that Republicans charged would catch small business owners in its net and cost more jobs during the recession.

Senate Finance Committee leaders met behind closed doors to thrash out ways to pay, including perhaps a tax on health insurers at a value of $100 billion over 10 years.