Health and Human Services secretary Kathleen Sebelius addressed local health care providers and community leaders on details of the soon to be implemented Affordable Care Act during a visit to Jacksonville, Florida's Sulzbacher Center on Sept. 16. (Bob Self/AP)

About 1,500 nurses squeezed into the hotel ballroom to give Health and Human Services Secretary Kathleen Sebelius a standing ovation before she’d even said hello. “This is so exciting!” whispered a nursing teacher from Grand Rapids, Mich.

There was extravagant applause when Sebelius said that some members of Congress consider defunding the Affordable Care Act “the only thing they’d like to do for the next three years of their lives.” There was more of the same when she added, “But here’s the real deal: This is the law.”

Anyone at that microphone would have been feeling the love by then — and thinking she was among allies. Sebelius told the almost all-female crowd at the Wednesday afternoon kickoff of the National League for Nursing convention in Washington that they were highly “informed validators” of the law Nancy Pelosi pushed up Capitol Hill three years ago and the Supreme Court declared constitutional last summer.

“Who better than you,’’ Sebelius asked rhetorically, to help explain the law ahead of Oct. 1, when Americans in every state and the District will start signing up for the health-insurance exchanges? Who better to talk up the program, biggest new social program in decades,as Hill Republicans throw themselves onto the tracks in front of the ACA train, even if it means shutting down the government?

Alas, Madam Secretary, some of those standing and clapping were just being polite. In conversations before and after your “Let’s go get ’em” talk, the health-care professionals at the Marriott Wardman Park were as divided as the rest of us. And just as confused about how 16 million previously uninsured will enroll, and what that will change.

Their objections aren’t partisan or ideological. No one mentioned abortion, worried about expanding the role of government or voiced concern that Americans could get “hooked” on a new entitlement.

Their concerns are specific and practical.

Sister Marie Buckley, who teaches nursing in Rockland County, north of New York City, doubts that penalties for opting out of coverage are harsh enough to nudge young, healthy people to sign up. The system is designed to have their premiums help offset the cost of care for those baby boomers who were sure they’d never get old or sick. She worries: Won’t a lot of younger folks figure, “If the fine is only $95, why pay” more than that for coverage that invincible me doesn’t need?

“Hospitals are really struggling as it is,’’ adds her friend Kathleen Hopkins. She sees the law as “a nightmare, because reimbursement is tied to a black-and-white standard” that harshly penalizes even “one little mistake” and could put some out of business.

Mandy Millet, dean of nursing at Northern Virginia Community College, was put off by her experience with the system in England, where she was born and where her mother died last fall: “My mom fell in the hospital and hit her head, and they said, ‘We can’t treat her for that,’ because she was there for outpatient cancer treatment. They wouldn’t give her an ice pack or let her lie down.”

Yes, she knows that the American system will remain primarily private and that the uninsured need care. While the “concept’s good, the reality might be very different,” she said.And will new standards keep nurses from providing the care and compassion that have always been at the heart of their mission?

There were also some strong advocates in the crowd: “It’s a misconception that this is for people who don’t work,’’ said Carmen Stokes, who described herself as “an old ER nurse” at Detroit’s Sinai Grace. She’s seen the uninsured and underinsured come in far too late, at far greater expense. “I get tired of people calling it Obamacare,’’ she said, when it’s about improving access and accountability.

What the staunchest supporters love — the law’s emphasis on a common good — might be exactly what worries the critics. Whose good matters more? Once, insurers viewed reconstruction after breast cancer as cosmetic and didn’t cover it. Maybe those days should come back, said Kathleen Poindexter of Lansing, Mich. Americans “think we always have to have the best,” she said, but “people have to understand that this is a paradigm shift.”

“Maybe you’re walking around and you’re able to work; you’re fine’’ after breast cancer, added Patricia Empie of Grand Rapids, and don’t really need reconstruction that costs a sum with which “I can give immunizations to thousands.”

Most of the conventioneer skeptics interviewed hope to be proven wrong, they volunteered. Maybe glitches can be fixed.

“It’s not clear what we’re supposed to do,’’ said Rachel Bertiz, who works in a hospital and teaches nursing at Montgomery County Community College. She sees chaos, questions and a switch to electronic medical records that’s going awfully slowly.

If someone spelled out exactly how nurses are supposed to be on the forefront of change, she’d be there. “Every day I see people without insurance,” she said. “As a nurse and someone who pays taxes, that worries me” too.