The extension affects only a small slice of Americans, who typically use these plans for less than a year as a stopgap policy between jobs, and is aimed at smoothing the transition into the new insurance system established by the law, according to White House officials, who asked for anonymity to describe the policy before the president’s remarks.

The Republican legislation would let insurers continue selling for a year current policies that don’t meet the Patient Protection and Affordable Care Act’s requirements to new customers, which White House officials said would undermine a central principle of the health law.

Boehner Skeptical

House Speaker John Boehner, an Ohio Republican, said before the president’s remarks that he is “highly skeptical” that the system can be modified through administrative measures.

Obama said he would defy Republican attempts to scuttle the law, known as Obamacare

“I will not accept proposals that are just another brazen attempt to undermine or repeal” the law, he said. “This fix won’t solve every problem for every person, but it’s going to help a lot of people.”

The debut of the insurance marketplace at the core of the law, Obama’s signature achievement, has been marred by flaws in the federal online exchange and by the insurance cancellation letters. In the debate over the law, Obama had repeatedly promised that Americans who liked their existing insurance plans would be able to keep them.

Program Flaws

Obama said he was “not informed directly” about how deeply flawed the website was in the weeks and days before its rollout on Oct. 1. He again apologized for assuring the public that they would see little change when the law took effect.

“There is no doubt that the way I put that forward unequivocally ended up not being accurate,” Obama said. A so- called grandfather clause that allowed policies in place before the law was enacted in 2010 was “insufficient,” he said.