WASHINGTON — President Obama is trying to persuade a weary public and wavering Democrats to get behind his frantic, late-stage push on health care, while Republicans dig in and demand starting from scratch after a year’s worth of work.

“Now, despite all the progress and improvements we’ve made, Republicans in Congress insist that the only acceptable course on health care is to start over. But you know what? The insurance companies aren’t starting over,” Obama said in his weekly radio and Internet address Saturday.

“I just met with some of them on Thursday, and they couldn’t give me a straight answer as to why they keep arbitrarily and massively raising premiums — by as much as 60 percent in states like Illinois. If we do not act, they will continue to do this.”

Republicans said they weren’t swayed.

“It’s not too late: We can, and we must, stop this government takeover of health care,” said Rep. Parker Griffith, a retired physician and a first-term congressman from Alabama who switched parties in December and delivered the GOP message.