LOS ANGELES — Los Angeles public school teachers reached a deal with officials Tuesday to end a weeklong strike that had affected more than a half-million students, winning an array of supplementary services after an era in education marked by attacks on traditional public schools and their teachers.

The deal showed the clout the teachers union has with Democrats in power in this city and this state. But union leaders said that what was perhaps more important to them was that the strike had provided an alternate narrative to the school choice movement that grew up around the idea that traditional public schools were factories of failure that needed to be broken up and rethought.

The deal includes caps on class sizes and hiring full-time nurses for every school, as well as a librarian for every middle and high school by the fall of 2020. The union also won a significant concession from the district on standardized tests: Next year a committee will develop a plan to reduce the number of assessments by half. The pro-charter school board agreed to vote on a resolution calling on the state to cap the number of charter schools. Teachers also won a 6 percent pay raise, but that was the same increase proposed by the district before the strike.

The settlement came after tens of thousands of teachers in the nation’s second-largest public school system marched in downtown Los Angeles and picketed outside schools for six school days, and after a round of marathon negotiating sessions over the holiday weekend.

The contract was ratified by an “overwhelming supermajority” of the roughly 30,000 members of the union, officials said Tuesday evening. Teachers are expected to be back in their classrooms Wednesday morning.

“Today is a day full of good news,” Mayor Eric Garcetti said during a news conference Tuesday morning at City Hall, as he stood alongside Austin Beutner, superintendent of the Los Angeles Unified School District, and Alex Caputo-Pearl, president of United Teachers Los Angeles. “This is a good agreement; it is a historic agreement; it gets to lower class sizes; it gets to proper support staff.”

“The strike is painful and had a cost,” the mayor added. “But there is no question to get here, the strike helped.”

The Los Angeles strike was the eighth major teacher walkout over the past year. A movement that calls itself Red For Ed spread from West Virginia to Oklahoma, Arizona and beyond. But the strike in Los Angeles was a union-led one against Democratic leaders who are usually on their side. It also was one of the first to highlight one of the most controversial questions in education: whether charter schools, which are publicly funded but privately managed, hurt traditional schools by competing with them for students and funding. Most charter schools are not unionized.

The agreement includes a pledge that the elected school board for the district will vote on a resolution asking the state to “establish a charter school cap” and create a governor’s committee on charter schools, according to a statement released by the union.

It was unclear how much practical effect the change would have, because there are already more than 1,100 charters in the state. Roughly 20 percent of all students in Los Angeles are enrolled in charter schools, according to state figures. California law allows 100 new charter schools to open each year, which is considered relatively liberal nationally.

Beutner and his allies on the Los Angeles school board have been vocal supporters of charter schools, which they say offer parents more choices. Charter schools have also been championed by prominent business leaders and philanthropists in Los Angeles, including Eli Broad, who backed Beutner’s selection as superintendent last year.

Some of the moves bolster traditional public schools after a long period that put heavy emphasis on creating alternatives to them, and on using students’ standardized test scores to hold schools and teachers accountable.

“I see this as a paradigm shift,” said Randi Weingarten, president of the American Federation of Teachers, who traveled to picket with Los Angeles teachers twice during the strike. “The elite types who use charters as a force for competition will see this as a big blow. We’re now seeing a mainstream shift toward neighborhood public schools with the goal being: Let’s make them work for all kids.”

The strike’s outcome pointed to a new direction on education for the Democratic Party, away from President Barack Obama’s agenda — which sought to expand high-quality charter schools and, at times, pushed back against teachers unions — and toward a more open embrace of the influence of organized labor on public education. Prominent Democrats who are running, or are considering running, for president, including Cory Booker, Sherrod Brown, Kirsten Gillibrand, Kamala Harris, Bernie Sanders and Elizabeth Warren, all issued statements in support for the striking teachers.

Supporters of charter schools pushed back on the idea of a cap Tuesday. “Placing a cap on the growth of charter schools puts the agenda of the education bureaucracy before the needs of public school students, and we cannot stand for that,” said Nina Rees, president and chief executive of the National Alliance for Public Charter Schools.

Caputo-Pearl said Tuesday that the past week had showed an “absolute groundswell” of support for Los Angeles’ public schools.

“We have seen over the last week something amazing happened,” Caputo-Pearl said. “We took on the idea of bargaining for the common good. Public education desperately needs attention.”

The strike drew attention to how California, one of the wealthiest and most liberal states in the country, spends relatively little on its public schools. As they announced the outlines of the deal, Garcetti, Beutner and Caputo-Pearl declined to give specific details on how the district would pay for the changes, but school officials said they would need more money from local voters and the state.

“We’re spending every nickel we have,” Beutner said. “It’s all in for schools. This is the start, not the end.”

Many of the changes — including class-size caps and full-time nurses at every school — would be phased in over time, officials said. Because those changes would occur over the next three years, the deal essentially punted on the question of how the district would come up with the $403 million needed to pay for the additional staff members. District officials said on Tuesday that they expect to propose a local parcel tax in 2020. Such a tax which would require the approval of two-thirds of voters in the sprawling district. Beutner also made it clear that he expected the attention to now turn to Sacramento for increased funding.

The state’s chronically constrained school spending is largely attributed to its property tax laws, and especially to Proposition 13, a ballot initiative passed in 1978 that drastically limits tax rates and makes increases difficult to enact. Affluent, fast-growing suburban communities have suffered less under the law than large urban systems like the Los Angeles Unified School District, where declining enrollment and rising costs for pensions and health care have created budget problems year after year.

While many educators and local leaders have called the strike a watershed moment for California public schools, it is far from clear whether there is a political willingness to change the statewide property tax laws. The union and district officials are both backing a ballot measure that would increase taxes on commercial, though not residential, properties in 2020.

The strike settlement is also a significant achievement for Garcetti, who has no formal authority over the school system. Although he publicly supported the teachers, he acted as a mediator of sorts and helped broker the deal during days of negotiations at City Hall. Before the strike, Garcetti had largely shied away from involvement with the public schools, but with the national spotlight on the strike and the mayor considering a presidential bid in 2020, he appeared eager to get involved during the past week.

Teachers in several other states, including Oklahoma and West Virginia, have won raises through statewide strikes that attracted wide public and political support.

Other major U.S. cities and states are now facing a possible school walkout, even as Los Angeles reached a settlement. Teachers in Denver began voting over the weekend on whether to strike after negotiations with the city’s school system failed to produce an agreement Friday, local news outlets reported. In Virginia, teachers are planning a statewide demonstration later in January. And teachers in Oakland, California, said they had drawn lessons from Los Angeles teachers and were preparing to vote on a strike.

With fewer than half the district’s students attending school during the Los Angeles strike, officials said the walkout had cost the district roughly $125 million in state financing that is distributed based on attendance.

A poll released by Loyola Marymount University on Tuesday showed that the overwhelming majority of Los Angeles residents continued to support the strike.

This article originally appeared in The New York Times.