WASHINGTON (CNN) -

Quick, can you hear it? That creaking sound from Washington is the nerves of congressional Democrats in response to the political firestorm raging around the health care law.

The botched rollout of the Affordable Care Act's vital new marketplaces, coupled with insurers notifying more than a million Americans that their policies were being canceled, raised questions about the administration competence and honesty in selling and implementing President Barack Obama's signature health care reforms.

Republicans still licking their wounds after last month's failed bid to dismantle the ACA by shutting down the government got a new chance to attack, keeping the issue in national headlines because of the problems rather than a successful launch of the enrollment process.

Obama apologized on Thursday night in an interview with NBC and said unspecified steps would be taken to help those losing coverage.

However, some Democrats facing re-election battles next year are joining Republicans in calling for the administration to delay provisions of the 2010 law that survived a Supreme Court challenge last year.

Here are four reasons why Democrats are nervous:

Website woes

The major problem has been the failure of the HealthCare.gov website that was set up to enroll people in new ACA health insurance exchanges starting on Oct. 1.

Instead of a comprehensive online portal for uninsured people or those who buy individual coverage to readily shop for policies online, the website became a symbol of government failure when most early visitors couldn't log in, got constant error messages, faced long delays and had their profiles disappear.

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Health care law rattling Democratic nerves