US President Barack Obama yesterday defended his broad healthcare 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.

Obama spent a sixth consecutive day pushing for his top domestic priority, with growing resistance on Capitol Hill – including from conservative Democrats.

"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 yesterday 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."

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

On Friday, he added a lastminute White House appearance to exhort law makers not to "lose heart" and urged deeper cost cuts to calm concern over the expense of covering millions of uninsured Americans.

But Republicans kept up their criticism. "The president and some Democrats insist we must rush this plan through," said Republican senator for Arizona Jon Kyl. "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 health­care 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.

House speaker Nancy Pelosi 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 law makers 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 changing the bill to produce more savings might require more time.

It likely won't be enough to convince Republicans. "It would empower Washington – not doctors and patients – to make healthcare decisions and would impose a new tax on working families during a recession," Kyl said. "They propose to pay for this Washington-run healthcare system by dramatically raising taxes on small business owners."

Kyl, the No 2 Republican in the Senate, said his party's proposed amendments should be considered. "These chang­es do not require government takeover of the healthcare system, or massive new spending, job-killing taxes or rationing of care," he said.

Obama, again, rejected the criticism. "We know there are those who will oppose reform no matter what," he said, repeating his pledge that his plan would not add to the federal deficit or deny patients' choices.