President Barack Obama, Vice President Joe Biden and Director of the White House Office of Management and Budget Sylvia Mathews Burwell, applaud HHS Secretary Kathleen Sebelius for her service during an event in the Rose Garden at the White House, on April 11, 2014 in Washington, D.C. (credit: Mark Wilson/Getty Images)

UPDATED: April 11, 2014 7:56 p.m.

WASHINGTON — Abruptly on the spot as the new face of “Obamacare,” Sylvia Mathews Burwell faces steep challenges, both logistical and political.

Burwell, until now White House budget director, was named by President Barack Obama on Friday to replace Health and Human Services Secretary Kathleen Sebelius, who oversaw the messy rollout of the health care overhaul. Now the new secretary must keep the complex program running smoothly and somehow help restore a cooperative dialogue with Republicans who are hoping to use the law’s problems to regain control of the Senate in November.

At an upbeat Rose Garden event, Obama showered praise on Sebelius, a hero for his party’s liberal base, whose impending retirement had been a tightly guarded secret.

The president ignored calls for Sebelius to resign last fall, after the website for consumers to enroll in new coverage experienced weeks of crippling technical problems. Last month, as it started to look like sign-ups would beat expectations, Sebelius approached the White House about stepping aside, officials said.

“Under Kathleen’s leadership, her team at HHS turned the corner, got it fixed, got the job done,” Obama said. “And the final score speaks for itself.” About 7.5 million people have signed up for subsidized private health insurance through the new law, exceeding an original target of 7 million widely thought to be unattainable because of the website problems.

Obama quickly pivoted to Burwell, 48, a low-profile Washington veteran now serving as his budget chief. He stressed her role last year in helping to end a government shutdown and reach a two-year budget deal with a politically divided Congress.

“Sylvia is a proven manager, and she knows how to deliver results,” Obama said.

Senate Finance Committee Chairman Ron Wyden, D-Ore., who will hold confirmation hearings for Burwell, said there’s an opportunity for her to move the health care debate beyond stalemate.

While a political truce is unlikely over Obama’s health overhaul, Wyden ticked off a list of other issues where Republicans and Democrats might be able to find compromise. Among them: revamping the way Medicare pays doctors, providing coordinated care for patients with chronic illnesses and using data to encourage delivery of quality health care at lower cost.

Although health care spending has grown at historically low rates during Obama’s tenure, a reviving economy could stoke cost problems anew for businesses, government programs and consumers.

Health and Human Services is a $1 trillion agency that plays a key role in American society and the economy. More than 100 million people receive coverage through Medicare, Medicaid, and now Obama’s health law. The secretary also oversees the Food and Drug Administration, which regulates a broad range of consumer products, and the Centers for Disease Control and Prevention, the front line for public health.

But Burwell could have her hands full addressing issues with the health care law, predicted Brookings Institution health economist Mark McClellan.

“Don’t underestimate the remaining implementation challenges for the Affordable Care Act,” said McClellan, who oversaw the rollout of the Medicare drug benefit for President George W. Bush. “It’s true that the first open enrollment season is over, but that was just the front end of the implementation process.”

Among those challenges:

— Keeping premiums affordable for 2015. Many younger people whose premiums would help offset the cost of care for older, sicker adults appear to have sat out the first sign-up season.

— Overhauling the sign-up process to make it more consumer-friendly. Supporters of the law say more in-person assistance is needed for the next enrollment season, which begins Nov. 15.

— Working with states that are still opposed to, or undecided about, the law’s Medicaid expansion. Nearly half the states have not signed on to the law’s mechanism for expanding coverage among low-income adults.

— Helping to guide administration policy on how to enforce the law’s penalties for individuals who remain uninsured and the medium- to large-sized businesses that do not provide affordable coverage to their employees.

She’ll be facing a Congress that’s unlikely to provide any additional funding to help the administration smooth over implementation problems.

Burwell has three tests immediately ahead, said former HHS Secretary Mike Leavitt, who also served under Bush. “Get confirmed. learn the department. prioritize the challenges.”

Burwell has a head start on the first two; how she’ll do on the third remains to be seen.

She was confirmed by the Senate 96-0 for her current post last year, and Obama said with a smile, “I’m assuming not much has changed since that time.”

As budget chief, Burwell is already familiar with the details of health care programs and how they work. Budget experts in both political camps agree that health care is the main driver of long-term growth in federal spending.

As she announced her resignation Friday, Sebelius called her work on the health care overhaul the “cause of my life.”

“We are at the front lines of a long-overdue national change,” she said.

Sebelius has served as Obama’s health and human services chief for five years, and helped steer the sweeping health law through Congress in 2010. But her tenure was marred by complaints from Congress that her department was not upfront about implementation problems. That seemed to be confirmed last October, with the dysfunctional launch of HealthCare.gov.

The problems frayed her close relationship with the White House. West Wing officials said they felt blindsided by the extent of the technical problems and installed a longtime Obama adviser to oversee fixes.

White House officials said Sebelius approached the president about stepping down a month ago, suggesting that the close of the six-month enrollment window marked a natural point for a transition. Officials said she also told the president he would be better served by a secretary who was less of a political target.

House Minority Leader Nancy Pelosi, a staunch supporter of the health care law, praised Sebelius as a “forceful, effective and essential” secretary.

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