US senators unloaded fresh attacks on the Obama administration's handling of the new health care law Wednesday, as the official overseeing the debut predicted "very low" early enrollment due to online sign-up troubles.

Five weeks into the rocky launch of the website through which millions of Americans are expected to register for insurance, Health Secretary Kathleen Sebelius faced criticism that the Affordable Care Act was putting the entire system in jeopardy, with one Republican accusing officials of lying about the impact of "Obamacare."

Last week Sebelius apologized to the nation for what she acknowledged was a "miserable" start to HealthCare.gov, and on Wednesday she again took the blame, saying "I am focused on fixing it, and I'm accountable."

But she acknowledged that the disastrous start will mean fewer initial enrollments.

"I can tell you our early enrollment numbers are going to be very low," Sebelius told the Senate Finance Committee.

"There was a memo internally that called for about a million people to be enrolled through December, but... we're updating those targets," she added.

Last week she said the system had already generated about 700,000 applications, but enrollment figures would not be released until mid-November.

Ending the crippling online glitches should lead to "more robust" enrollment numbers, she said, but until that happens there will be "a struggle getting significant numbers to sign up."

But she insisted the law was already working well for millions by no longer allowing insurers to deny coverage because of pre-existing conditions, impose coverage caps, or charge women more for health care.

Senator Orrin Hatch and other Republicans pointed to higher insurance costs, and thousands of consumers getting notices that their existing plans were being dropped despite Obama's pledge that consumers who liked their policies could keep them.

"Put simply, there is a long track record of broken promises and untruthful answers to both this committee and the American people with respect to how this law would work and the impact it would have," Hatch told Sebelius in the committee hearing.

"I hope that will stop today. No more caveats, no more excuses, no more spin. Just give us the truth," he said.

The White House has been under fire for weeks about the botched website debut, with Republicans accusing the administration of ignoring potential pitfalls in order to press ahead with Obama's signature domestic policy achievement.

Republicans demanded that Sebelius explain why she and others insisted the website, HealthCare.gov, go live on October 1 despite insufficient testing and warnings in August within her own Health and Human Services Department that there were critical security and privacy issues requiring attention.

Sebelius shot back: "No one, I would say, suggested that the risks outweighed the importance of moving forward."

Committee chairman Max Baucus, a Democrat, joined in the frustration, asking "Why keep limping along" instead of temporarily shutting down the troubled website until the kinks are worked out.

"We've been advised that that actually doesn't help," Sebelius responded, saying "it's better to do routine upgrades" while the system is running.

Authorities have created a "punch list" of priorities for getting the website fully operational by November 30 as promised, and Sebelius said her teams identified "a couple of hundred functional fixes" that take priority.

Senator Pat Roberts of Kansas, a state where Sebelius served as governor, accused her of knowing full well that the exchanges would not be ready October 1.

"In your zeal to implement this law, not warnings, not advice, not counsel would deter you from implementing the exchanges," said Roberts, who repeated his request for Sebelius to resign.

"I believe to protect the administration, you chose to ignore these warnings, and as a result, you have put our entire and one-sixth of our economy in jeopardy."

Baucus said it was imperative that Sebelius stay on board to see the fixes through, preferably before the November 30 deadline.

"There's no room for error," he said.

Obama, in a bid to counter the stream of criticism, headed to Texas Wednesday to highlight the role of volunteers who help consumers enroll through the health care exchanges.

© 2013 AFP