Education Secretary Arne Duncan gestures as he speaks about the importance of universal access to preschool at J. Ormond Wilson Elementary School in Washington. (Cliff Owen/AP/File)

Christina Waters’s cellphone rang, and she looked down to see that the number was blocked. She knew immediately it was U.S. Education Secretary Arne Duncan, just calling to check in.

It has been that way since Waters attended a 2009 church picnic in Chicago and came away with a bullet lodged in her head from stray gunfire. She suffered hearing loss in one ear, and her college dreams were delayed. But she pushed forward, with encouragement from Duncan, who has known her since elementary school. Now 24, Waters is studying kinesiology at Sam Houston State University in Texas.

Waters belongs to a circle of strivers that Duncan has quietly cultivated, students across the country who are clearing hurdles that would discourage many others. He calls regularly to offer support and advice.

That unfiltered, direct contact has been key in shaping Duncan’s belief that poor students hold the same potential as their affluent peers but face more obstacles to a high-quality education in America’s public schools. Trying to correct that imbalance, Duncan has injected an unusual amount of federal influence into traditionally local decisions about public education.

The result is that most Americans now accept public charter schools as an alternative to neighborhood schools, most teachers expect to be judged in some measure on how well their students perform on standardized tests, and most states are using more demanding K-12 math and reading standards.

Education Secretary Arne Duncan tours Wakefield High School in Arlington, Va. (Dayna Smith/For The Washington Post)

But Duncan’s policies have led to side effects that people across the political spectrum feel have hurt more than they’ve helped. Conservatives say those closest to students — local communities — lost power to decide what’s best for them. Liberals complain about an unhealthy focus on math and reading and about overtesting, leading to an “opt-out” movement that saw hundreds of thousands of students boycott tests this spring.

“The record will show these policies brought about minimum improvement,” said Jack Jennings, founder of the nonpartisan Center on Education Policy and author of a new book about education politics. “They also did considerable harm.”

Duncan faces a political backlash that threatens to undercut his power and erase some of his most influential work. The bipartisan warmth he enjoyed on Capitol Hill has yielded to critics from the left and the right, including an odd alliance between tea party conservatives and the teachers unions. This week, both houses of Congress began debating legislation that would seriously dial back the education secretary’s legal authority; the Senate began Tuesday and the House approved a bill Wednesday.

“The question is not whether we’re going to put handcuffs on Arne Duncan,” said Lanae Erickson Hatalsky of Third Way, a centrist think tank. “The question is how many handcuffs.”

As other Obama Cabinet members have come and gone, Duncan has become the longest-serving member of the original group. His own staff has turned over multiple times. And now, even his wife and children have moved back to Chicago, eager to return to life beyond the Beltway.

But Duncan is still here, a onetime professional basketball player who is hanging on until the final buzzer.

He wants to fight for the changes he has advocated and said in a recent interview he feels an urgency to keep pushing toward unmet goals in the waning months of the Obama administration.

He calls his job the dream of a lifetime: “I still pinch myself some days.”

And even if he wanted to leave Washington, it’s hard when the president is your buddy.

Duncan and Obama, whose friendship dates to 1990s Chicago, decompress together. There are family weekends at Camp David, Super Bowl gatherings and Fourth of July pool parties at the White House, and the occasional burger run. They have played pickup basketball together for years, though Obama, 53, has traded hoops for golf after a few too many mishaps on the court.

“His risk/reward ratio isn’t where he wants it to be,” said Duncan, 50, who still plays, but recently broke a finger.

In a town where many like to talk, Duncan is regarded as a good listener. “Arne is a great sounding board for the president,” said Valerie Jarrett, the president’s close friend and adviser.

Duncan’s ties to the White House, combined with the president’s own interests, elevated education within the administration’s domestic agenda. But as Washington has taken a stronger hand, those decrying federal overreach have multiplied.

“I’ve never seen both Democrats and Republicans want to curb the authority of the federal Department of Education the way they want to now,” said Randi Weingarten, president of the American Federation of Teachers.

Duncan has tried to straddle the deep national divide about the best way to improve public education, working between those who believe that competition, accountability and market forces are the best route and others who argue for heavier investment to address the many needs of poor children who are increasingly filling public schools.

To Duncan, that has meant expanding public charter schools; promoting higher academic benchmarks such as the Common Core State Standards in math and reading; holding teachers accountable for student progress as measured by test scores; enrolling more low-income children in preschool; and a desire to invest in “wraparound services” such as medical care, mentoring and family services.

Duncan has exploited two tools that gave him great leverage.

First, he got $4.3 billion from Congress — money designed to prop up the economy after the 2008 recession — and created Race to the Top, a national contest that required cash-starved states to adopt Duncan’s education policies to compete for a chance at a grant.

Then he focused on states struggling under No Child Left Behind, the 2002 education law that was due for replacement in 2007. Widely considered to be unrealistic, the law remains in effect because Congress has failed to rewrite it. Duncan began excusing states from its most onerous aspects as long as they adopted his education policies. Today, 42 states and Washington, D.C., hold these temporary, conditional waivers.

Rep. John Kline (R-Minn.), who chairs the House Committee on Education and the Workforce, calls the waivers “convoluted.”

“They’re temporary and conditional on them doing what the secretary wants them to do,” said Kline, the author of a GOP alternative bill that would block the education secretary from making such demands of states. “That’s a terrible, terrible way to do policy.”

Washington state lost its waiver in 2014 after lawmakers rejected Duncan’s requirement that it use student test results to evaluate teachers, which experts increasingly say is not a reliable way to identify good and bad teachers. The state lost control over $40 million in federal dollars as a result.

Sen. Patty Murray (Wash.), the ranking Democrat on the Senate education panel, opposed the waivers but said congressional inaction on No Child Left Behind gave Duncan little choice. “He has had to administer a law that doesn’t work,” Murray said.

The increased federal muscle made waves.

“It is about as top-down as you can get,” said Weingarten, the AFT president. “It’s based on a theory of total and complete mistrust that teachers, parents, districts and states won’t do right by children.”

Under No Child Left Behind, states used test scores to judge schools. But under Duncan, they had to use student scores to evaluate individual teachers. Infuriated, the National Education Association called for Duncan’s resignation.

Conservatives have accused Duncan of federal intrusion, even violating the Constitution, especially when it comes to the Common Core State Standards.

The administration played no role in developing the standards, which were created by a bipartisan group of governors and state school leaders. But Duncan required states to adopt “college and career ready” K-12 standards — generally understood to mean the Common Core — if they wanted a waiver. And when it came to awarding competitive grants, Duncan gave extra points to those states that adopted “college and career ready” standards.

Forty-three states and the District quickly adopted the Common Core in math and reading. But boasts from Duncan and Obama about the speedy embrace fueled pushback against “Obamacore” among tea party activists.

The fight over Common Core became politically toxic, having less to do with the standards than with the idea that local communities had lost control over their schools. And the political battle has spread to Congress.

Sen. Lamar Alexander (R-Tenn.), who chairs the Senate education panel and served as education secretary under President George H.W. Bush, has worked with Murray to draft a bipartisan replacement for the federal education law that would restrict the education secretary’s authority to influence state academic standards, assessments or teacher evaluations.

Alexander praised Duncan’s ability and said they share the same mission: high standards, teacher evaluations and charter schools. “We just have a different path to those goals,” Alexander said. “His is through Washington, and mine is through the states.”

The conflict has made Duncan “radioactive,” said Jeffrey Henig, professor of political science and education at Teachers College, Columbia University. “He’s reduced, in terms of what he can realistically accomplish in the time he has left.”

That’s frustrating for Duncan, who recounted how one senator confided that he supported universal preschool — an idea Duncan has been promoting for two years — but would not publicly back any plan for the federal government to fund it.

“That’s, like, my political lesson in Washington,” Duncan said. “Are you here to make a difference? . . . Or are you here to say you’re a fancy senator?”

Duncan’s zeal for education is rooted in his childhood. He grew up in the integrated neighborhood of Hyde Park, near the University of Chicago, where his father taught psychology. But he spent much of his time in neighboring poor, black North Kenwood, where his mother, Sue, founded a tutoring center before he was born.

Sue Duncan created a safe space in the inner city where children could find stability, academic achievement and opportunities beyond the streets.

“Every day, I think about what she did on one corner of 46th Street,” Duncan said. “I try to take the lessons I had from the time I was a child and give more kids a chance in life.”

Sue Duncan and her three children played pickup basketball at the University of Chicago, where Sue would sometimes foul a young law professor named Barack Obama.

Basketball and education became passions for 6-foot-5 Arne Duncan — he played at Harvard and then professionally in Australia — and they also dominated his conversations with Obama. When Obama was elected president, Duncan was running the Chicago public school system.

“I definitely didn’t want to come to Washington,” Duncan said. “I came here because my friend became the president. . . . And it was just this crazy, chance of a lifetime to try and have an impact.”

He saw an opportunity to attack problems on a national scale, in a way that his mother never could.

But progress for the nation’s K-12 students has been uneven. High school graduation rates are at an all-time high, and dropout rates are down. But average math and reading scores for high school students have flatlined since 2008, and they improved only marginally among 9- and 13-year-olds, according to federal data.

One of Duncan’s greatest regrets is his failure to get Congress to invest $75 billion to create universal preschool for low-income children.

“The tide, which ran with him early and especially because of the windfall in recovery funds that made Race to the Top possible, has now reversed to a degree,” Henig said. “Some of that might be attributable to overreaching on his part, but the backlash against Common Core, federally initiated testing pressures, etc., also has a lot to do with shifting partisan politics during a second-term presidency.”

As Duncan tries to hold his ground in Washington and fight political pressures to reverse course, he maintains those ties to the young people around the country who inspire him to push on.

Christina Waters is working this summer for Chicago’s WNBA team, thanks partly to Duncan. When they spoke recently, she confessed she was depressed because she was still chasing a bachelor’s degree at 24.

“He told me that it’s okay, that everyone finishes on their own time,” Waters said. “He told me he was proud of me, and that just meant so much. And he just encouraged me to overlook any distractions.

“He said just keep going.”

Correction: An earlier version of this story incorrectly reported that Duncan required states to adopt “college and career ready” standards to compete for grants. While Duncan required states to adopt such standards if they wanted waivers, the adoption of such standards were not required for grants but gave states extra points in the competition for them. The story has been updated.