The stakes couldn’t be higher for Obama and for Burwell, who will be 51 when the Obama administration comes to an end.

Former Treasury Secretary Robert Rubin, for whom she was chief of staff between 1995 and 1997, said Burwell would be on his short list to lead Treasury in another Democratic administration, saying she has a “terrific political sense.”

Meanwhile there’s the presidential election looming, with Republican candidates who want to repeal the 2010 law ready to spotlight any stumble.

How PPACA performs in the next 12 months could determine its fortunes.

Political football

“The ACA, even though it’s helping a bunch of people, isn’t untouchable in the political process,” said Dylan Roby, a professor at the University of Maryland School of Public Health. Burwell and her team “will need to make sure the website works fairly flawlessly, they need to make sure they see increases in enrollment.”

Individuals are now signing up for health insurance for the third time in the new markets created by the law. And while the main insurance shopping website has overcome the glitches that plagued its rollout, it’s still not smooth sailing for PPACA.

Premiums are going up 10 percent or more in many markets, though about 84 percent of customers get subsidies to help them afford coverage. Burwell herself has said enrollment may not increase as much as some had expected.

Burwell acknowledged that people have had some trouble picking the right policies, with some deciding based mainly on how expensive policies were, rather than on what’s covered.

To help, the government is now adding to its shopping website estimates of how much an individual should expect to spend in total under different plans, giving a better idea of what out- of-pocket costs will be.

Struggling carriers

Meanwhile, some insurers have struggled to make a go of it financially. Twelve of the 23 nonprofits set up by the law are failing.

UnitedHealth Group Inc., the largest U.S. health insurer, has warned it may withdraw from PPACA marketplaces because it can’t make money.

Health-care stocks have more than doubled since Obama signed the act, buoyed by millions of new customers with health policies bought with ACA subsidies, and shares of insurers like UnitedHealth Group Inc. have tripled.

Yet investors have become more jittery recently, amid signs the health law’s gains are slowing, or even reversing.

Hospital-stock volatility is the highest it’s been since late 2011, and managed-care-stock volatility has shot up as well.

Burwell said she’s focused on the bigger picture. “We need to continue to move on the path of transformation,” she said. “The Affordable Care Act, while we all focus on it very much in terms of access, was about affordability and quality and transforming the fundamentals of the system as a whole.”

She pointed out that about 17.6 million people gained coverage under the law who otherwise wouldn’t have it.

That includes the expansion of Medicaid coverage to more low-income people, and children who are allowed to stay on their parents’ policies longer than before PPACA.

For adults, the uninsured rate has fallen to about 11.6 percent, from 17.1 percent just before the law went into effect.

Employer burden

A provision of the law that requires companies to give workers health insurance had been derided as a job killer.

A Bloomberg review of company conference-call transcripts and interviews with major U.S. employers found that, instead, it’s turned out to be not much of a burden at all.

Beyond the coverage expansion, the law is changing how care is paid for and delivered in the U.S., Burwell said.

It’s pushing doctors and hospitals to collaborate more closely and to improve the quality of the care they deliver.

Government actuaries estimate that health-care spending in the U.S. will rise by about 5.8 percent annually through 2024. It increased an average of 6.9 percent a year in the decade before the law was passed.

Scarce time

The secretary isn’t the only one watching the clock. “Time is our scarcest commodity. We’re all very aware of it now as we approach the last year,” said Treasury Secretary Jacob J. Lew, who was Burwell’s boss in the Clinton administration. “She’s always about her list, and about using her time to take care of the things that are most important.”

When asked whether she might be the first female Treasury secretary, the woman who gets to sign the $10 bill that will feature a woman, Burwell laughed for a moment before answering.

“I’m deeply focused on what I’m working on now, and enjoying it, and it’s challenging every day,” she said. “I think we will see what happens in terms of all of those issues, and I look forward” after the Obama administration ends, “to observing and watching.”

Varied resume

Burwell replaced Kathleen Sebelius, the former Kansas governor who oversaw the troubled early days of the health law. For just more than a year before that, she led the OMB.

Those were her first Washington posts since she served all eight years in Bill Clinton’s administration, starting at the National Economic Council, before becoming Rubin’s chief of staff at Treasury and then deputy director of OMB under Lew.

In between the Clinton and Obama administrations, she ran the global development program at the Bill & Melinda Gates Foundation and was president of the Walmart Foundation.

She graduated from Harvard University with a degree in government and studied philosophy, politics and economics at Oxford University as a Rhodes Scholar.

In an on-stage interview with Carlyle Group founder David Rubenstein at the Economic Club of Washington, Burwell said she’d learned a few lessons from her foundation work. One, she said, was to define, at the start, the goal of a project.

The other, she said, is her approach to problem solving. “Which is, what’s the problem you’re trying to solve, that circle? What’s the solution space? And what are you good at? Aim to every day work in that sweet spot.”

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