President Barack Obama on Saturday defended his broad health care overhaul, calling it fiscally sound and urging Congress not to squander its moment to pass reform. Stepping up their criticism, Republicans cast the plan as a financial burden that shouldn't be rushed.

Adopting an aggressive tone, Obama spent a sixth consecutive day pushing for his top domestic priority. Growing resistance on Capitol Hill _ including from conservative Democrats _ has left White House officials worried they face a tougher route to legislation than they had anticipated.

"This is what the debate in Congress is all about: whether we'll keep talking and tinkering and letting this problem fester as more families and businesses go under and more Americans lose their coverage," Obama said Saturday in his weekly radio and Internet address. "Or whether we'll seize this opportunity _ one we might not have again for generations _ and finally pass health insurance reform this year, in 2009."

The president's comments come at the end of a week of tumult for the legislation.

All week, Obama tried to project confidence on a subject that has dominated his schedule. During a closed-door meeting with Jewish leaders on Monday, he joked that the only thing more difficult than passing health care legislation might be negotiating peace in the Middle East.

And on Friday, he added a last-minute White House appearance to exhort lawmakers not to "lose heart" and urged deeper cost cuts to calm concern over the huge expense of covering millions of uninsured Americans.

He continued that push Saturday as Republicans kept up their criticism.

"The president and some Democrats insist we must rush this plan through," said Sen. Jon Kyl, R-Ariz. "Why? Because the more Americans know about it, the more they oppose it. Something this important needs to be done right, rather than done quickly."

On Friday, two House committees approved their portions of the sweeping health care bill over Republican objections. That left one more panel to act, but Democrats facing tough re-election bids or representing conservative districts demanded additional measures to hold down costs.

Given the complexities, as well as fresh calls for delay in the Senate, House Speaker Nancy Pelosi, D-Calif., opened the door to pushing off a vote past the early August timeline she and Obama laid out weeks ago. While Pelosi has long said the House will vote on legislation by the time lawmakers leave on vacation at the end of July, she hedged for the first time.

"We have to see what the Senate will do," she said, before suggesting that changing the bill to produce more savings might require additional time.

It likely won't be enough to convince Republicans, who are in near-unison in opposing the Democrats' plan.

"It would empower Washington _ not doctors and patients _ to make health care decisions and would impose a new tax on working families during a recession," Kyl said in the GOP's weekly address. "They propose to pay for this new Washington-run health care system by dramatically raising taxes on small business owners."

Kyl, the Senate's No. 2 Republican, said his party's proposed amendments should be considered.

"These changes do not require government takeover of the health care system, or massive new spending, job-killing taxes or rationing of care," he said, seeking to string together the biggest fears of Obama's plan to challenge the popular president.

Obama, again, rejected the criticism out of hand.

"Now, we know there are those who will oppose reform no matter what," Obama said. "We know the same special interests and their agents in Congress will make the same old arguments and use the same scare tactics that have stopped reform before because they profit from this relentless escalation in health care costs."

Obama also repeated his pledge that his plan would not add to the federal deficit or deny patients' choices.

The president said he and his wife, Michelle, "don't want anyone telling us who our family's doctor should be _ and no one should decide that for you, either.

"Under our proposals, if you like your doctor, you keep your doctor. If you like your current insurance, you keep that insurance. Period, end of story."

That's a pledge, however, that's beyond Obama's control. His plan leaves companies free to change their health plans in ways that workers may not like or to drop insurance altogether.

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On the Net:

Obama address: http://www.whitehouse.gov

GOP address: http://www.youtube.com/user/gopweeklyaddress