US senators unloaded fresh attacks on the Obama administration's handling of the rollout of the new health care law Wednesday, with one Republican accusing officials of being "untruthful" about its impact.

Five weeks into the rocky launch of the website through which millions of Americans are expected to register for health insurance, Health Secretary Kathleen Sebelius faced criticism that the Affordable Care Act was putting the entire health care system in jeopardy.

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

She insisted, however, that 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.

But Senator Orrin Hatch and other Finance Committee 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 at a 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 obfuscating 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,, go live on October 1 despite insufficient testing and warnings in August by inspectors in her own Health and Human Services Department who said there were critical security and privacy issues that required 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 up to full speed by the end of November as promised, and Sebelius said her teams have 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 health care system and one-sixth of our economy in jeopardy."

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