LOS ANGELES (Reuters) - The union for more than 30,000 striking Los Angeles teachers clinched a tentative contract deal with the second-largest U.S. school district on Tuesday, paving the way for classes to resume for nearly half a million students after a weeklong walkout.

Hours later, the president of the United Teachers Los Angeles union, Alex Caputo-Pearl, announced that rank-and-file members were voting to ratify the 3-1/2-year deal by a “vast supermajority,” thus officially ending the strike.

Teachers who walked off the job on Jan. 14 in their first strike against the Los Angeles Unified School District (LAUSD) in 30 years were due back in the classroom at all 1,200 schools on Wednesday.

The union president and two other principals in the talks, LAUSD Superintendent Austin Beutner and Los Angeles Mayor Eric Garcetti, who served as mediator, all characterized the settlement as historic.

The deal, announced at a City Hall news conference by the three leaders, acceded to many of the union’s demands for improving classroom conditions that all sides in the labor dispute agreed have suffered from decades of underfunding.

Caputo-Pearl credited the striking teachers with transforming a contract campaign into a social movement that reawakened people to the long-neglected difficulties facing public education in California, and across the country.

He vowed to leverage momentum from the strike into a long-term quest for additional resources at the state level, including a campaign to roll back property tax restrictions widely seen as stunting fiscal support for public schools.

The agreement, capping five days of marathon negotiations that ended at dawn on Tuesday, includes an immediate 6 percent across-the-board pay raise for teachers, slightly less than the 6.5 percent hike they sought.

But Caputo-Pearl said defining features of the deal will phase in significant class-size reductions while hiring hundreds more librarians, nurses and guidance counselors. The district also agreed to remove a provision of the old contract allowing it to unilaterally waive caps on class sizes.

Teachers gather at Grand Park in Los Angeles for a rally after their union reached a deal with school district officials on a new proposed contract in Los Angeles, California, U.S., January 22, 2019. REUTERS/Alex Dobuzinskis

The deal provides for student numbers in all high school math and English classes to drop immediately by at least seven, Caputo-Pearl said.

In addition, the school board would consider a non-binding resolution urging the state legislature to cap the expansion of independently operated charter schools, which the union argues divert resources from traditional classroom instruction.

DEAL HAILED AS MAJOR UNION VICTORY

Caputo-Pearl told a celebratory rally of thousands of teachers outside City Hall, site of the final round of talks, that they had achieved a major victory in attaining the bulk of their contract objectives while galvanizing public support.

“It is very rare that you go to the bargaining table with as many demands as we had and you win almost every single one of them,” Caputo-Pearl added.

Leaders of the school district - which does not answer to the mayor - had insisted throughout the talks they largely supported the union’s goals but lacked funds to satisfy the demands without risking insolvency.

Beutner became a target of criticism from teachers by resisting their demands to commit more of the district’s $1.8 billion reserve to easing overcrowded classrooms and hiring more support staff. He said it was needed to retain financial stability in the face of rising pension and healthcare costs.

“We’re spending every nickel we have,” Beutner told the news conference.

Caputo-Pearl said that ultimately some of the district’s reserves were tapped to close the deal. According to its accounting, the district will spend $403 million just to hire support staff and cut class sizes.

Beutner said Los Angeles still had a long way to go, citing figures showing that LAUSD spends roughly $16,000 per pupil per year, compared with $22,000 in New York City public schools.

The Los Angeles strike followed a flurry of teacher walkouts over salaries and school funding in several states last year, such as Arizona, Oklahoma and West Virginia.

In contrast to those states, the Los Angeles teachers faced a predominantly Democratic political establishment more sympathetic to their cause.

Labor tension still simmers in other big-city school districts. Results are expected this week of Saturday’s strike authorization vote by Denver teachers after they rejected a contract offer. Teachers in Oakland, California, are also due to vote this week on strike authorization.

Caputo-Pearl said a preliminary tally of electronic votes cast by two-thirds of LAUSD teachers showed more than 80 percent in support. A final tabulation of paper ballots will be announced on Wednesday, he said. The L.A. school board is expected to formally approve the deal on Jan. 29.