President Barack Obama's Health and Human Services SecretaryKathleen Sebelius is resigning, paying the price for the chaotic initial rollout of hissignature health care law, officials said.Obama will nominate Sylvia Mathews Burwell, his current budget director, who hasa reputation as an accomplished manager, to replace Sebelius on Friday, theofficials said.The administration hopes that the departure of Sebelius will draw a symbolic lineunder the early implementation period of the law, which had a botched debut due toa malfunctioning sign-up website and other teething problems.The administration was forced into an emergency effort to fix the site and succeeded to such an extent that 7.5 million people have now signed up for healthinsurance under the new law -- a figure that defied expectations.Obama and top aides spent last week declaring victory over skeptics who argued that the law -- the most sweeping US social reform in decades -- would never work orthat Americans would refuse to sign up.But the stuttering debut of so-called Obamacare provided fresh ammunition toRepublicans who are using the law's unpopularity to blast vulnerable Democratsahead of November's mid-term elections."I thank Secretary Sebelius for her service. She had an impossible task: nobody canmake Obamacare work," said House Republican majority leader Eric Cantor onTwitter.Obama will look to Burwell, if she is confirmed, to smooth out remaining glitcheswith the law before the next registration period opens in November.- 'Partisan sniping' - "The president wants to make sure we have a proven manager and relentlessimplementer in the job over there, which is why he is going to nominate Sylvia,"White House Chief of Staff Denis McDonough told The New York Times.The White House apparently decided that the end of the sign-up period on March 31marked an appropriate time for Sebelius, who has been in the job for five years, tomove aside.Sebelius "thought that it was time to transition the leadership to somebody else,"McDonough told the Times."She does hope -— all of us hope -— that we can get beyond the partisan sniping."And House Democratic Minority Leader Nancy Pelosi insisted that Sebelius's "legacywill be found in the 7.5 million Americans signed up on the marketplaces so far, the3.1 million people covered on their parents' plans, and the millions more gainingcoverage through the expansion of Medicaid." But Republicans quickly moved to exploit the resignation, previewing what could bea fiery Senate confirmation process for Burwell.Republican National Committee Chairman Reince Priebus said Obama could name a new health secretary but could not fix endemic problems with his health care law."The next HHS Secretary will inherit a mess -- Americans facing rising costs, familieslosing their doctors, and an economy weighed down by intrusive regulations," hesaid."No matter who is in charge of HHS, Obamacare will continue to be a disaster and will continue to hurt hardworking Americans."Republicans argue that Obamacare forced Americans to ditch existing health plans,will hike the cost of insurance and will hamper small businesses and hurt jobcreation.Obama countered earlier this month that the Obamacare law was working, despiteearly problems, and that it would bed down and remain a part of American life.He seemed to have the struggle to implement the law in mind when he paid tributeto former president Lyndon Johnson, who passed the Civil Rights Act 50 years ago,and argued that the presidency should be used to promote change and equality.What president Johnson understood was that equality required more than theabsence of oppression -- it required the presence of economic opportunity," Obamasaid in Texas."A decent job, decent wages, health care -- those too were civil rights worth fightingfor.