US President Barack Obama has apologised to Americans whose health insurance plans have been cancelled as a result of his signature health law.
In recent weeks, insurance companies have reportedly cancelled policies that do not meet strict requirements under Mr Obama's 2010 healthcare overhaul.
"We didn't do a good enough job in terms of how we crafted the law," he said in an interview with NBC News.
But a senior Republican labelled his remarks a "half-hearted apology".
During his campaign for the passage of the Affordable Care Act, also known as Obamacare, Mr Obama repeatedly insisted that people who liked their health insurance policies would be able to keep them.
But it now appears that millions of people who purchased plans on the private individual market rather than receive health coverage from the government or their employers may in fact have to buy new, possibly more expensive plans.
"I am sorry that they are finding themselves in this situation based on assurances they got from me," Mr Obama said.
"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 health law's supporters have said most people thrown off their health plans will be able to buy better insurance policies at better prices, especially those eligible for subsidies provided under the health law.
The opposition Republicans, who have fought the president's healthcare law at every turn, have seized on the reports of the policy cancellations. Some have gone so far as to accuse Mr Obama of lying to the public during his campaign for the law's passage.
Even some of Mr Obama's fellow Democrats have suggested the administration delay parts of the law's implementation, including a requirement that people carry health insurance or face a penalty.
Mr Obama's remarks on Thursday came after weeks of serious problems with healthcare.gov - a website established under the law - which allows consumers to shop for private health insurance plans.
Among other issues, it has been plagued by long wait times to sign up for an insurance plan and serious flaws on the back end where customers' data are processed and sent to insurance companies.
Mr Obama has vowed the website will be repaired.
The Republican response to Mr Obama's remarks was swift, with Senate Minority Leader Mitch McConnell saying "if the president is truly sorry for breaking his promises to the American people, he'll do more than just issue a half-hearted apology on TV".
Thursday's television interview was the latest effort by Mr Obama to win public support for the embattled healthcare law.
On Wednesday he travelled into the heart of Republican territory to talk up the measure.
"We are going to get this done," he told a crowd in Dallas, Texas.
The law's new coverage requirements for health insurance plans have been blamed for the policy cancellations.
Its other provisions include establishing the healthcare.gov website and others run by the states; mandates that individuals carry insurance or pay a tax penalty; and subsidies to assist in the purchase of the insurance.
It also expands eligibility for the Medicaid government health programme for the poor.