DENVER - President Obama often professes his desire to shake up public education while also working with teachers unions. But a question hangs over this week's gathering of hundreds of labor leaders and school officials: Can he do both at the same time?

More than any of his predecessors, Republican or Democratic, Obama has pushed a reform agenda centered on teachers. He wants the good ones to earn more money and the bad ones to leave the profession. He wants test scores to count in evaluations. He wants personnel shake-ups at failing schools.

Accomplishing such goals often means confronting union rules that protect teacher tenure and pay scales based on seniority rather than student achievement. Education Secretary Arne Duncan said Tuesday that labor and management can overcome hurdles through what he called "tough-minded collaboration."

But some analysts say the administration's quest for union support could dilute results.

"The political challenge is, how do you do this without alienating an important part of your constituency?" said Frederick M. Hess of the conservative-leaning American Enterprise Institute. You could end up with a civil war in the Democratic Party. That's why what we've seen from the administration is a lot of two steps forward, one step back."

Administration officials say Obama's policies have spurred progress on a host of fronts, leading states across the country to take steps toward performance pay, charter school expansion and tenure reform.

Many Republicans say they applaud elements of Obama's reform agenda that are at odds with union traditions.

"I do have some respect for the fact that the president and Secretary Duncan have challenged their constituencies to go out of their comfort zone," said Tony Bennett, superintendent of public instruction in Indiana and a Republican.

At the start of the two-day conference here in Denver, Duncan pushed further into politically sensitive terrain. He said schools and unions should rethink policies related to who gets laid off during budget crises, an issue in many places. Critics of unions say that "last-in, first-out" rules too often force young teaching talent out of schools.

"My view is that we need to take a hard look at the impact of staffing rules, seniority and equity issues," Duncan told union and school officials from more than 150 school systems.

Union leaders are in no rush to abandon seniority, but they said they are too often typecast as enemies of reform.

Dennis Van Roekel, president of the 3.2 million-member National Education Association, said that test scores are a poor measure of teacher performance but that every teacher should be able to show evidence of student learning. He noted that NEA affiliates last year helped Delaware and Tennessee win large shares of Obama's $4 billion Race to the Top fund.

"We've been in a good place with [Obama officials] the whole time," Van Roekel said. "That doesn't mean we don't ever have disagreements. We both agree absolutely that the way it is right now in public education can't remain. The status quo is not acceptable."

Randi Weingarten, president of the 1.5 million-member American Federation of Teachers, said affiliates in Baltimore, New Haven, Conn., and elsewhere are breaking ground with contracts that put student achievement first. She said teachers are not the only ones responsible for progress.

"Management has more responsibility than anybody else to get things done," she said. "The Obama administration has completely taken them off the hook."

Duncan said school boards and superintendents should get more scrutiny. He organized the conference with the NEA, the AFT and other groups to showcase a dozen school systems billed as innovators. Among the systems were Montgomery County, where teachers participate in a peer-review program that can force low performers out of a job, and Hillsborough County, Fla., where officials are designing a teacher-salary framework tied to student achievement and peer evaluation.

Kevin Singer, superintendent in Topeka, Kan., and Mary Masters, the local union president there, said they came to the conference to learn how schools are using test scores in evaluations. "That's been for years one of the things that's pretty scary" to teachers, Singer said.

David James, superintendent in Akron, Ohio, and Akron's local union president, Jeff Moats, said they were looking to improve evaluations. But they said they disagreed with each other on the merits of seniority protections in times of layoffs.

Asked about Obama, Moats recalled a speech last year in which the president expressed support for a Rhode Island school board that had voted to fire teachers at a struggling school. Subsequently, the Central Falls High firings were rescinded. But he and others here said Obama's words still rankled.

"I was shocked and I was disappointed" at Obama's statement on Central Falls, said Laura Rico, president of the ABC Federation of Teachers, based in a Los Angeles County district that officials call a model. "But I believe the president wants to do good for students and teachers. I just would like him to listen more to people who are the voice for teachers and students."