"This has to be ripped out by its roots," House of Representatives Speaker John Boehner, the top Republican in Congress, said of the 2010 law on the CBS program "Face the Nation." Boehner added: "We will not flinch from our resolve to make sure this law is repealed in its entirety."

The House, controlled by Republicans, has scheduled a vote on July 11 to repeal the law. The Democratic-led Senate, as it has done in the past, is certain to block any repeal legislation.

The U.S. Supreme Court on Thursday upheld the law, Obama's signature domestic policy achievement and the most sweeping overhaul since the 1960s of the unwieldy U.S. healthcare system. The ruling was written by conservative Chief Justice John Roberts and joined by the court's four liberals.

"I think the thing that the American people want is for the divisive debate on healthcare to stop," White House Chief of Staff Jack Lew said on "Fox News Sunday."

"I think that what we need to do is get on with the implementation now, and that's what we intend to do," Lew added.

The healthcare law battle promises to figure prominently in the November 6 election in which Obama is challenged by Republican Mitt Romney, who as Massachusetts governor pushed through a state healthcare overhaul with provisions similar to Obama's plan.

A Reuters/Ipsos poll released on Sunday showed public support for the law rising to 48 percent after the ruling from 43 percent before the court's decision.

The U.S. system, unlike other rich countries, is a patchwork of private insurance and restrictive government programs. The United States pays more for healthcare than any other country, but about 50 million of the roughly 310 million Americans still have no insurance.

The law was meant to bring coverage to more than 30 million of the uninsured and slow soaring medical costs. Critics deride the law as "Obamacare" and say it meddles too much in the lives of individuals and the business of the states.

'SINGLE WORST PIECE OF LEGISLATION'

Senate Minority Leader Mitch McConnell said Republicans will insist that the Democrats who control the chamber hold a vote before the election on repealing the law.

"If I'm the leader of the majority next year, I commit to the American people that the repeal of 'Obamacare' will be job one," he said on "Fox News Sunday."

McConnell said he would use a process called "reconciliation" in the 100-member Senate to permit a simple majority to pass a repeal of the law rather than the customary 60 votes. McConnell had criticized Senate Democrats for using that same process in passing the bill in 2010.

"Yes, that could be done with a simple 51 votes," he said.

"This is the single worst piece of legislation that's been passed, certainly in modern times. And it will be an issue, a big issue, in the fall election," McConnell said.

"We've got one last chance here to defeat Obamacare. We can do that in the November election," added McConnell.

McConnell labeled the law's "individual mandate" provision - requiring most people to obtain health insurance by 2014 or pay a financial penalty - a middle-class tax increase.

Asked whether a similar provision in Romney's healthcare law in Massachusetts was also a middle-class tax increase, McConnell said, "Well, I think Governor Romney ought to speak for himself about what was done in Massachusetts."

The White House and fellow Democrats refuse to label as a tax the law's penalty on people who decline to obtain health insurance - even though the Supreme Court upheld the constitutionality of the "individual mandate" only because it was permissible under the congressional power to levy taxes.

"It's a penalty. It's something that only 1 percent of people - who can afford insurance and choose not to get - it will pay," Lew said on CNN's "State of the Union."

Nancy Pelosi, the top House Democrat, added on NBC's "Meet the Press": "It is a penalty for free riders."

Asked what Republicans would do - if they succeed in repealing Obama's law - to provide coverage to the tens of millions of Americans currently with no insurance, McConnell said: "That is not the issue. The question is how can you go step by step to improve the American healthcare system. It is already the finest healthcare system in the world."

"We're not going to turn the American healthcare system into a western European system," he added, referring to government-run systems that provide near universal coverage.

(Additional reporting by Vicki Allen, Paul Eckert, Lesley Wroughton; Editing by Vicki Allen)

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