(Reuters) - The largest union for teachers in Oklahoma gave lawmakers in the cash-strapped state an April 1 deadline to approve pay raises for some of the lowest-paid educators in the country or face a shutdown of public schools, its president said on Wednesday.

The move came a day after teachers in West Virginia ended a nine-day strike that closed schools statewide, with officials approving a 5 percent pay raise for all state workers.

Alicia Priest, president of the Oklahoma Education Association, said the union was putting Oklahoma lawmakers on notice that they needed to pass an education budget by April 1 that contained significant pay hikes.

“If that budget doesn’t include a meaningful pay raise for teachers and support professionals, and additional funding to restore cuts to Oklahoma classrooms, OEA calls for statewide school closures beginning April 2,” she said in a message posted on the union’s Facebook page.

According to National Education Association estimates for 2016, Oklahoma ranked 48th, followed by Mississippi at 49 and South Dakota at 50, in terms of average U.S. classroom teacher salary.

Republican state Representative Rhonda Baker, who chairs the House of Representatives Common Education Committee, said in a statement that one of her pivotal concerns was “to ensure education in our state is fairly funded and that any law affecting our schools provides an actual benefit to students and educators.”

Teachers in Oklahoma have warned over the past several days of a walkout because of budget cuts that have led to four-day school weeks in the state and teachers’ average salaries trailing those in West Virginia, which ranked 46th nationally last year, according to the NEA.

For the past few years, Oklahoma has battled budget deficits stemming from the 2014 collapse in oil prices that hit its large energy industry and slammed state revenue.

The Oklahoma union has said it is seeking a $10,000 pay raise over three years for teachers and a $5,000 increase for support personnel. Oklahoma secondary school teachers had an annual mean wage of $42,460 as of May 2016, according to the U.S. Bureau of Labor Statistics.

In neighboring Texas, teachers earned about 30 percent more, according to Bureau of Labor figures.

The Oklahoma union had set an April 23 deadline for the Republican-controlled legislature to act, but moved that date up at the request of its 40,000 members.

“The anger and frustration caused by the inaction of the Oklahoma legislature is palpable,” Priest said.