WASHINGTON (AP) — President Barack Obama ridiculed lingering opposition to his 10-month-old health care law Friday and vowed to oppose efforts to repeal it, underscoring his commitment to his signature legislative achievement despite the new reality of a divided Congress.

Days after delivering a State of the Union message in which he called on Democrats and Republicans to work together, Obama made clear in a speech to supporters that he's open to compromise on the issue only on the margins — a "tweak" here or there, but not major changes.

"I am not willing to just refight the battles of the last two years," said the president, who saw his popularity plummet and some in his own party distance themselves amid the scalding, partisan debates over the health care law. "I'm not open to efforts that will take this law apart without considering the lives and the livelihoods that hang in the balance."

The House of Representatives, with Republicans newly in control, voted to repeal the health care law last week. Republicans have vowed to seek a similar vote in the Senate, but are unlikely to prevail as Democrats still control that chamber. The White House has dismissed the effort as an empty gesture.

Yet, the president is not ignoring the congressional challenge. He stood up for the bill in his State of the Union earlier this week and reiterated his support with a mocking rebuttal to the GOP on Friday in a speech to the consumer group Families USA, which advocated for the health law.

"You may have heard once or twice that this is a job-crushing, granny-threatening, budget-busting monstrosity. That's about how it's been portrayed by opponents. And that just doesn't match up to the reality," said the president.

He argued that since he signed the bill 10 months to extend coverage to 30 million uninsured, the economy has grown and small businesses are offering health care to employees, many for the first time, because of tax credits offered in the law. He said that repealing the law would add to the deficit — though if that happened it would be only because the many taxes, fees and Medicare cuts in the law would be lost. And the president said the elderly are benefiting from a stronger Medicare, and those who fell into a gap in Medicare's prescription drug program are receiving relief.

"I can report that Granny is safe," he said.

Obama reiterated his support for changing a small business tax reporting provision that both parties agree is onerous, and he said he'd also consider ideas dealing with medical malpractice reform. However, the president has never endorsed the caps on lawsuit payouts that would generate the biggest savings in the medical malpractice area, and are favored by Republicans.

"I believe that anything can be improved," he said.

As the president spoke, the Health and Human Services Department issued a report saying that a combination of new competitive insurance markets and government subsidies could bring costs down significantly for people who purchase their coverage individually once the law fully takes effect in 2014.

Senate Republican Leader Mitch McConnell, R-Ky., dismissed the findings.

"More promises of lower premiums for some people at some point in the future is little comfort to the millions who are already seeing higher premiums or won't be able to keep the coverage they have as the president promised," McConnell said. "We need to repeal this bill and replace it with commonsense reforms."