With more than 8 million Americans now dependent on medical coverage through Obamacare, the law may finally be cemented into the foundation of U.S. society.

The response easily beat a Congressional Budget Office prediction of 6 million, and the agency says it expects at least 7 million more people will enroll in private plans after the sign-up period for 2015 opens in November.

Between now and then, politicians will try to make the law’s effects on consumers a key issue in the November congressional elections. Foes say the law makes insurance too expensive, opens enrollees to high out-of-pocket costs and limits medical choices. Backers say expanded access to care for all Americans and substantial cost reductions for lower-income people outweigh any disruptions in previous coverage.

“Realistically, it’s not going to be repealed,” said Bill Hoagland, a former top adviser to Republican Bill Frist, the retired Tennessee senator, in a telephone interview. “What I think Republicans need to do is move on and focus on those changes in the law that would improve its acceptability to Republicans, as opposed to continuing to talk about repeal.”

Congressional Republicans continue to insist that their top political goal remains repealing the Patient Protection and Affordable Care Act. Without an alternative policy to expand access to health care, however, that position now entails casting millions of Americans out of insurance coverage.

“This thing is working,” President Barack Obama said in a news conference at the White House yesterday.

Medicaid Expansion

At least six million people gained coverage under Obamacare provisions that have expanded Medicaid in 26 states and allowed adult children to stay on their parents’ plans, Obama said. Next year, the budget office says the number of people covered under the Medicaid expansion will increase to about 11 million.

The administration’s success at enrollment has drawn notice from insurers.

“The size of the overall market is positive,” Gail Boudreaux, an executive vice president at UnitedHeath Group Inc. who leads the company’s commercial health plans, said in a conference call with Wall Street analysts yesterday. “Our bias is to increase our participation in 2015.”

Kevin Counihan, the chief executive officer of the insurance exchange in Connecticut, one of the most successful in the country, said he expects one new company to join the four plans offering coverage on Access Health CT next year. About 79,000 people in the state signed up for exchange plans this year, twice as many as state officials anticipated.

‘New Culture’

“This whole state came together to try to incorporate this as a value for the state and to create a new kind of culture of assuming that this is a right of citizenship in the state of Connecticut,” he said in a phone interview.

Even if Republicans win the Senate in November congressional elections, giving them control of the entire Congress for the first time since 2006, they pose little threat to the health law with Obama still in office, said Hoagland, the former Frist adviser.

The main vulnerability in the law now comes from insurers, at least one of which -- WellPoint Inc. -- has said it may propose large premium increases next year. Insurers will file 2015 rates in May and June, and any increases are likely to be announced by the end of the summer, posing political difficulty for Democratic congressional candidates, Hoagland said.

‘Real Problems’

“It could very well be that some of those rate increases will be significant,” Hoagland said. “If you start to see double-digit premium increases, that could cause real problems for the plans, and possibly for Obamacare going forward.”

In his comments yesterday, Obama said that about 35 percent of enrollees in the federal insurance exchanges are younger than 35. That’s a four percentage-point rise since March 1, indicating a surge of sign-ups by young adults and children. That’s good news for the administration, as insurers build their rates in part by weighing the number of healthy customers they believe they’ll get compared with the number of costly older and sicker consumers.

Longer term, provisions of the law aimed at reducing health costs and improving care must be shown to work before Obamacare can be declared a success, said Doug Holtz-Eakin, the executive director of the American Action Forum, an advocacy group in Washington that is critical of Obama’s administration.

“This law is more than people being covered in exchanges and Medicaid,” he said in a telephone interview.

Care Coordination

There is not much evidence yet that programs designed to encourage better coordination of care between doctors and hospitals have been broadly effective, he said. Tests of new payment models for hospitals and other health providers under Medicare, the government-run health program for the elderly, are inconclusive and haven’t yet been expanded.

“There was a vision of things in here that were going to revolutionize the way care is delivered,” Holtz-Eakin said. “That’s an enormous disruption and it’s not obvious that those things are working. So, it’s still vulnerable.”

The debate expected to gain energy as the next election draws near was framed during the president’s remarks on the law yesterday, and the Republican response.

Obama called on Democrats to embrace the law in their campaigns, and for Republicans to propose practical changes that would improve it.

The House Speaker, Republican John Boehner of Ohio, and the Senate Republican leader, Mitch McConnell of Kentucky, responded by accusing the law of causing chaos in the health-care system. They questioned Obama’s enrollment figures, which included no information on how many of the 8 million in exchange plans previously had insurance or paid their first premium, the final step to sign up.