President Barack Obama has acknowledged difficulties with the roll-out of a key health website, adding people are working "24/7" to get it running smoothly.
He has faced a storm of criticism over the glitches that have afflicted healthcare.gov, through which millions of Americans are expected to buy insurance.
Customers have had trouble signing on, enrolling and getting accurate quotes for policies.
"As you may have heard, the site isn't working the way it's supposed to yet," Mr Obama said in his weekly address to the nation.
"That's frustrating for all of us who have worked so hard to make sure everyone who needs it gets health care."
Mr Obama said the site had had more than 20 million visits and nearly 700,000 people have applied for cover -- proof of the high demand for "quality, affordable health care choices."
"And that's why, in the coming weeks, we are going to get it working as smoothly as it's supposed to. We've got people working overtime, 24/7, to boost capacity and address these problems, every single day."
Republicans, who are vehemently opposed to his health insurance reforms, have seized on the website's launch problems to bash the administration.
Mr Obama said it was "interesting to see Republicans in Congress expressing so much concern that people are having trouble buying health insurance through the new website.
"Especially considering they've spent the last few years so obsessed with denying those same people access to health insurance that they just shut down the government and threatened default over it."
Mr Obama said he would work with opponents to improve the law -- formally known as the Affordable Care Act -- but that "it's well past the time for folks to stop rooting for its failure."
He added: "(Some people) have poked fun at me this week for sounding like an insurance salesman. And that's okay. I'd still be out there championing this law even if the website were perfect."
On Friday, Jeffrey Zients, who is overseeing the project, told reporters a general contractor had been hired to fix the website and that it should be running smoothly by late November.
Obamacare, as it is known, requires most Americans to have health insurance from 2014 or face a fine.
Contractors say the site's complexity -- it links customers to federal databases and those of 170 insurance firms -- has been a key factor in its poor start.
