Even as the health care bill, once the top priority of President Barack Obama, is still in a limbo, all the president's men stepped up attacks on the insurers asking them to justify premium hikes.

In an attempt that is widely viewed as a tactic to mobilize public support and persuade lawmakers to push US health-care legislation, Obama administration's top health asked the insurance companies to "publicly justify premium hikes."

White House officials are garnering support of American public for the biggest reform in US health care that still faces opposition from Republicans and some Democrats.

Health and Human Services Secretary Kathleen Sebelius questioned US top insurers UnitedHealth Group Inc., WellPoint, Aetna Inc. and Cigna Corp. in a letter asking them to disclose show how much of premium would go customers' medical care and how much is administrative costs.