By MICHAEL D. SHEAR
WASHINGTON â€” Kathleen Sebelius, the health and human services secretary, is resigning, ending a stormy five-year tenure marred by the disastrous rollout of President Obamaâ€™s signature legislative achievement, the Affordable Care Act.
Mr. Obama accepted Ms. Sebeliusâ€™s resignation this week, and on Friday morning, he will nominate Sylvia Mathews Burwell, the director of the Office of Management and Budget, to replace her, officials said.
The departure comes as the Obama administration tries to move beyond its early stumbles in carrying out the law, convince a still-skeptical public of its lasting benefits, and help Democratic incumbents, who face blistering attack ads after supporting the legislation, survive the midterm elections this fall.
Officials said Ms. Sebelius, 65, made the decision to resign and was not forced out. But the frustration at the White House over her performance had become increasingly clear, as administration aides worried that the crippling problems at HealthCare.gov, the website set up to enroll Americans in insurance exchanges, would result in lasting damage to the presidentâ€™s legacy.
Even last week, as Mr. Obama triumphantly announced that enrollments in the exchanges had exceeded seven million, she did not appear next to him for the news conference in the Rose Garden.
The president is hoping that Ms. Burwell, 48, a Harvard- and Oxford-educated West Virginia native with a background in economic policy, will bring an intense focus and management acumen to the department. The budget office, which she has overseen since April of last year, is deeply involved in developing and carrying out health care policy.
â€œThe president wants to make sure we have a proven manager and relentless implementer in the job over there, which is why he is going to nominate Sylvia,â€ said Denis R. McDonough, the White House chief of staff.
Last month, Ms. Sebelius approached Mr. Obama and began a series of conversations about her future, Mr. McDonough said. The secretary told the president that the March 31 deadline for sign-ups under the health care law â€” and rising enrollment numbers â€” provided an opportunity for change, and that he would be best served by someone who was not the target of so much political ire, Mr. McDonough said.
â€œWhat was clear is that she thought that it was time to transition the leadership to somebody else,â€ he said. â€œSheâ€™s made clear in other comments publicly that she recognizes that she takes a lot of the incoming. She does hope â€” all of us hope â€” that we can get beyond the partisan sniping.â€
Republicans seized on Ms. Sebeliusâ€™s departure to heap even more criticism on the law she helped pass and carry out. â€œNo matter who is in charge of H.H.S., Obamacare will continue to be a disaster,â€ said Reince Priebus, the chairman of the Republican National Committee. Senator Mitch McConnell of Kentucky, the Republican leader, said her resignation was â€œcold comfort to the millions of Americans who were deceived about what it would mean for them and their familiesâ€ under the health care law.
The resignation is a low point in what had been a remarkable career for Ms. Sebelius, who as governor of Kansas was named by Time magazine as one of the five best governors in the country and was even mentioned as a possible running mate for Mr. Obama in 2008. The two had bonded when Ms. Sebelius endorsed his presidential bid early in 2008, becoming one of the highest-profile Democratic women to back him over Hillary Rodham Clinton, and helping him deliver a big win in the Kansas caucus.
White House officials were quick to point out the many successes during Ms. Sebeliusâ€™s tenure: the end to pre-existing conditions as a bar to insurance, the ability for young people to stay on their parentsâ€™ insurance, and the reduction in the growth of health care costs. In addition, Ms. Sebelius helped push through mental health parity in insurance plans and worked with the Department of Education to promote early childhood education.
Ms. Sebelius said in an interview on Thursday that she had always known that she would not â€œbe here to turn out the lights in 2017.â€
â€œMy balance has always been, when do you make that decision?â€ she added.
The president had been under pressure for months to fire Ms. Sebelius. But he had resisted, in part because he did not want the Department of Health and Human Services to undergo more upheaval amid all the problems plaguing HealthCare.gov, and in part because of his general reluctance to publicly rebuke top officials.
In November, Mr. Obama defended the secretary, saying in an interview with NBC News that she â€œdoesnâ€™t write code; yeah, she wasnâ€™t our I.T. person.â€ As recently as last week, Jay Carney, the White House press secretary, rejected any suggestion that Ms. Sebelius would be fired.
On Thursday, Mr. McDonough praised Ms. Sebelius as â€œa fierce advocate,â€ and said she had been â€œtenacious in her beliefâ€ in the presidentâ€™s health care law. â€œSheâ€™s fearless in her defense of this idea at the heart of the Affordable Care Act,â€ he said. â€œThe president has commented to me countless times how much he admires that.â€
But the Affordable Care Act faces a range of obstacles, political and otherwise, in the months ahead, and Mr. Obama is hoping that Ms. Burwell can smoothly steer the department and bring stability to its operations. In addition to the midterm elections, in which the health care law is the target of a flood of negative ads, the administration is grappling with policy questions: how it will levy the penalty on individuals who lack insurance, how much premiums will go up in the coming year, and how ultimately to administer the requirement that employers provide insurance.
Ms. Sebelius was not Mr. Obamaâ€™s first choice to lead the department; he wanted former Senator Tom Daschle in the job, but Mr. Daschle withdrew after acknowledging that he had underpaid his taxes for several years. She was hailed as a gifted political leader in Kansas who could work with legislators of both parties. But those skills were less evident in Washington, and she became a more distant figure within the administration.
In addition to the political battles over the passage and carrying out of the Affordable Care Act, she clashed with conservatives over contraception, and faced frequent calls for her political head by Republicans after the health care website failed to function properly last year.
In hearings on Capitol Hill, Ms. Sebelius sometimes grew rattled under questioning by lawmakers. In one hearing at the end of October, Ms. Sebelius declared that HealthCare.gov â€œhas never crashed.â€
â€œIt is functional,â€ she added, â€œbut at a very slow speed and very low reliability, and has continued to function.â€
She made that statement even as large screens in the hearing room showed a live shot of the website with a page that said: â€œThe system is down at the moment. We are experiencing technical difficulties and hope to have them resolved soon.â€
An appearance on â€œThe Daily Show With Jon Stewartâ€ last October went even worse. Mr. Stewart challenged her to â€œsign up for Obamacareâ€ before he could download every movie ever made. â€œWeâ€™ll see which happens first,â€ he joked. She struggled to defend the website and the law.
The television appearance prompted headlines like â€œKathleen Sebeliusâ€™s â€˜Daily Showâ€™ Disasterâ€ and accusations from Republicans that she was being misleading. Democrats squirmed at her stiff and halting performance, which did little to inspire confidence.
But Ms. Sebelius has not been at the center of public attention in recent weeks. Her national television exposure has been limited after the poor public performances, but she has continued to make small appearances and has been active on Twitter to press for people to sign up for insurance. She submitted to another questioning before a Senate committee on Thursday and later acknowledged that the idea of not doing â€œa hearing every three weeks sounds pretty good to me.â€
The presidentâ€™s choice of Ms. Burwell to lead the Department of Health and Human Services places a relative outsider at the helm of one of the governmentâ€™s largest bureaucracies. Ms. Burwell has led the presidentâ€™s budget office since taking over for Jacob J. Lew, who is now the Treasury secretary.
Ms. Sebelius said she hoped â€” but did not expect â€” that her departure would represent the beginning of a more cooperative period in Washington to make health care better.
â€œIf I could take something along with me,â€ she said, it would be â€œall the animosity.â€