By Lisa Lerer and Margaret Talev - 2012-09-10T04:01:00Z

Republican Mitt Romney said he would keep parts of President Barack Obamas health care law, shifting his focus to independent voters as polls showed the president gained support after the Democratic convention.

Both candidates focused on health care yesterday as Obama wrapped up a two-day bus tour across the swing state of Florida by attacking Romneys proposal to change Medicare.

Romney, speaking in an interview on NBCs Meet the Press, said he would replace Obamas health care law with his own plan while keeping some popular provisions including coverage for people with pre-existing conditions. The Obama administration contends that requiring insurers to cover those people, without also mandating that almost everyone have insurance, would cause prices to soar.

Im not getting rid of all health care reform, said Romney. Of course there are a number of things that I like in health care reform that Im going to put in place.

Obamas post-convention Florida bus tour showed signs of a gain in intensity at the rallies. His audience in heavily Puerto Rican Kissimmee was so fired up that he said he was tempted to just say thank you and leave the stage.

An audience of 6,000 at his final stop in West Palm Beach broke into a sing-along before he took the stage, as the speakers played Al Greens Lets Stay Together. He told the crowd that while he knew he was preaching to the choir, now he needed them to go out and preach to the unconverted.

Romney, 65, has made opposition to the health care law a central theme of his campaign, saying one of his first actions in office would be to seek to repeal it.

On coverage for people with pre-existing conditions, Nobel- prize winning economist and New York Times columnist Paul Krugman wrote yesterday that such a requirement, without an insurance mandate, would lead healthy people to opt out of insurance, leaving behind a high risk, high cost pool.

Its not as easy as keeping some of the pieces without a requirement that individuals obtain insurance, Obama campaign spokeswoman Jen Psaki told reporters. Romney needs to explain his proposal with details and math, she said.

More:

Romney Says He Would Keep Parts of Obama Health Care Law