About 5 percent of all teachers in K-12 schools have walked off the job so far in 2018, marking the highest such level for work stoppages since 1992, according to a new analysis.

The educators have been protesting long-stagnant wages caused by constraints on state and local budgets, and the activity is expected to contribute to a potential pro-Democratic tide in the fall elections.

"Our figures for 2018 don’t yet include the teacher strikes around Washington state in September — or the big ones that may still be ahead this fall in Los Angeles and Oakland," said Jasmine Kerrissey, a faculty member of The Labor Center at the University of Massachusetts, Amherst, which compiled the data based on Labor Department reports, in a column for the journal Labor Notes.

Teachers unions argue the walkouts have energized teachers politically. The National Education Association has reported that approximately 550 educators are on the fall election ballot, based on its own survey of federal, state, and local elections.

The stoppages includes walkouts in North Carolina, Arizona, Colorado, Oklahoma West Virginia, and Kentucky. The wave may not have completed yet, either. Los Angeles teachers are reportedly considering a walkout. The 5 percent figure does not include walkouts involving higher education, such as more than 53,000 University of California teachers walking off in May.

Several of the strikes have been successful for the educators. Arizona Republican Gov. Doug Ducey signed a 19 percent pay increase over three years for teachers following April walkouts. Oklahoma teachers received average pay raises of $6,100 following strikes in April as well.

The unions have been spurred to action in part by the the Supreme Court's decision earlier this year in the case Janus v. American Federation of State, County and Municipal Employees. The justices ruled five to four that it was unconstitutional to force nonunion public sector workers to financially support unions, a previously common practice in labor contracts that was a major source of revenue for groups like NEA.

The union has said it anticipates losing 14 percent of its membership due to the ruling and has cut its budget by $28 million in anticipation. Teachers unions have argued that fear of declining influence has prompted their members to take more direct action.

[Also read: Pennsylvania lawmaker wants to ban public school teachers from talking politics in the classroom]