Republican presidential hopeful Mitt Romney said Sunday he will keep some of Barack Obama's controversial healthcare reforms if he wins November's election, breaking from a prior whole-scale rejection of the plan.

"Of course there are a number of things that I like in healthcare reform that I'm going to put in place," he said in an interview broadcast Sunday on NBC's Meet the Press.

Republicans have pledged to repeal "Obamacare" – legislation that has become the focus of a furious backlash from Republicans. Paul Ryan, the party's vice-presidential pick, has described the affordable care act as a "Ponzi scheme that would make Bernie Madoff proud". Romney himself has described the legislation as a "job killer" that "puts the federal government between you and your doctor".

But the former Massachusetts governor said Sunday there were a number of pieces of the legislation he would keep if elected, including making sure that people with pre-existing conditions can get insurance. Romney also said he would allow young adults to keep their coverage under their parents' health insurance.

"I say we're going to replace Obamacare. And I'm replacing it with my own plan," Romney said. "And even in Massachusetts when I was governor, our plan there deals with pre-existing conditions and with young people."

The interview came as it emerged that Obama had received a larger boost than Romney in the polls following their respective conventions. According to Scott Rasmussen's latest poll Obama now leads Romney 49% to 45%, his biggest lead since March 17 and his best approval rating of the year. Obama also has a four-point lead in the most recent Gallup and Reuters/Ipsos polls.

Rasmussen said: "The president's bounce began the night after Bill Clinton spoke to the convention and received rave reviews. Sixty-six percent of voters nationwide have a favourable opinion of the former president. Democrats overwhelmingly believe Clinton and Obama have similar views on how to fix the economy, but few Republicans and unaffiliated voters share that assessment."

He said the president had made significant gains in voters aged 40-64.

The poll Sunday comes even after disappointing jobs figures released Friday that showed the US added just 96,000 jobs in August. Obama has spent the weekend defending his record on the economy and attacking Romney's plans. In the swing state of Florida on Saturday Obama summed Romney's platform up as: "Tax cuts, tax cuts, gut a few regulations, some more tax cuts."

In an interview aired Sunday on CBS's Face the Nation, Obama further criticised his opponent for refusing to consider tax increases on America's super-rich as a way to help reduce the deficit.

He said:"You can't reduce the deficit unless you take a balanced approach that says, 'We've got to make government leaner and more efficient, but we've also got to ask people – like me or governor Romney, who have done better than anybody else over the course of the last decade and whose taxes are just about lower than they've been in the last 50 years – to do a little bit more."

Romney attacked Obama's record on the economy on Sunday, stating: "This does not look like a recovery."

He also tackled Democratic claims that his tax policies will favour the rich. "We're not going to have high-income people pay less of the tax burden than they pay today. That's not what's going to happen," he said.

Romney said he would keep taxes down by closing loopholes but declined to provide an example of a loophole he would close.

"I can tell you that people at the high end, high-income taxpayers, are going to have fewer deductions and exemptions. Those numbers are going to come down. Otherwise they'd get a tax break. And I want to make sure people understand, despite what the Democrats said at their convention, I am not reducing taxes on high-income taxpayers," Romney said.