"I am sorry that they are finding themselves in this situation based on assurances they got from me," Obama told NBC News in a Thursday interview at the White House.

"We've got to work hard to make sure that they know we hear them — and we are going to do everything we can to deal with folks who find themselves in a tough position as a consequence of this."

The president's admission came as Capitol Hill Republicans — and even members of his own party — stepped up attacks on Obamacare in recent days and amid reports that underscored new problems with the Patient Protection and Affordable Care Act.

House Speaker John Boehner said on Thursday that Obama’s apology was "certainly in order, but what Americans want to hear is that the president is going to keep his promise."

He noted that House Republicans would vote next week to allow Americans to keep the healthcare plans they liked.

"If the president is sincerely sorry that he misled the American people, the very least he can do is support this bipartisan effort," the Ohio Republican said in a statement. "Otherwise, this apology doesn’t amount to anything.”

Boehner's office released a video on Thursday attacking Obama's "walk back" on the coverage promises, saying in a statement that "Democrats are right to be worried."

The Boehner statement called Obama's "tweaking" of his earlier promises "a whopper."

And Senate Minority Leader Mitch McConnell slammed Health and Human Services Secretary Kathleen Sebelius' admission that convicted felons might have been hired to work as Obamacare "navigators," giving them access to enrollees' private information.

“Americans who’ve lost their insurance and find themselves forced onto the exchanges, the last thing they need is to worry about some felon stealing their identity," the Kentucky Republican said on the Senate floor.

Yet the White House has known since 2010 that millions of Americans could lose their insurance under Obamacare, NBC reported nearly two weeks ago, but Obama has since said in numerous speeches, “if you like your health plan, you will be able to keep your health plan.”

In a speech at a healthcare summit earlier this week, Obama added a major caveat: "Now, if you had one of these plans before the Affordable Care Act came into law and you really liked that plan, what we said was you can keep it, if it hasn't changed since the law passed."

Obama’s comments were made in a speech to supporters at the summit, sponsored by Organizing for Action, USA Today reports.

Under Obamacare, about 5 percent of the population is expected to buy their own insurance, NBC reports.

Since Obamacare's individual mandate took effect on Oct. 1, millions of Americans have received cancellation notices — forcing them them to seek out new plans, often with lesser coverage or with higher premiums.

According to NBC, HHS data from July 2010 estimated that “40 to 67 percent” of the 14 million consumers affected by Obamacare's individual mandate could lose their policies because of turnover in that market.

Those who are covered by Medicare or Medicaid — about 80 percent of the population, NBC reports — are not affected by the Obamacare individual mandate.

Still, the White House has repeatedly denied that President Obama deliberately misled Americans, contending that Obamacare could not have anticipated that insurance companies would change existing plans because of the new healthcare law.

Sebelius and White House spokesman Jay Carney have said that Americans switching coverage under Obamacare will obtain better-quality coverage.

“What we're talking about here is the 5 percent in the country who currently purchase insurance on the individual market,” Carney told NBC last month. “And that market has been like the Wild West. It has been under-regulated, it is the place where Americans have most keenly felt the challenges posed by the insurance system in this country.”

Sen. Max Baucus, the chairman of the Senate Finance Committee that questioned Sebelius on Wednesday, called Obamacare’s problems “unacceptable.”

The Montana Democrat, a key author of the healthcare plan, openly worried in April that the Obamacare rollout could become "a train wreck."

“It has been disappointing to see members of the administration say they didn’t see the problems coming,” he said in his opening statement at the committee’s hearing on Wednesday.

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