Barring a last-minute contract deal, Denver teachers said they are prepared to strike on Monday after state officials declined a request by the city’s public school system to intervene.

In Oakland, Calif., this week, teachers who have been working without a contract since July 2017 overwhelmingly voted to go on strike — probably this month — if a pact cannot be reached with the school district there.

The anticipated labor unrest follows the six-day teachers strike in Los Angeles, which ended last month with concessions by the Los Angeles Unified School District for higher pay, smaller classes and support from the school board for a cap on the number of charter schools.

The Los Angeles strike was the first major teachers labor action of the new year following walkouts in 2018 in at least half a dozen states. That included Colorado, where thousands of teachers went on strike for 2½ weeks over pay.

The protracted labor strife in the teaching profession reflects years of educator frustration over salaries and school funding. Many teachers pay hundreds of dollars out of their own pockets to buy basic supplies for their classrooms.

Colorado’s recently elected Democratic governor, Jared Polis, announced Wednesday that his administration would not intervene in the labor dispute between Denver Public Schools and the Denver Classroom Teachers Association, clearing the way for a strike.

The Denver teachers union, which represents most of the 5,600 teachers in the 90,000-student district, is demanding a salary increase. Some educators say their pay is so low they have to work a second job to get by.

Denver Public Schools Superintendent Susana Cordova’s administration has offered a raise, but the union says it is not enough. The district said it is still hoping to make a deal and has called for more negotiations this week.

“No teacher wants to strike,” Denver teacher and union president Henry Roman said in a statement. “We would rather be teaching students in our classrooms. But when the strike starts, we will be walking for our students. … DPS must improve teacher pay to keep quality, experienced teachers in Denver classrooms.”

Meanwhile, in Chicago, teachers at four charter schools, which are publicly funded but privately operated, went on strike this week. They are demanding salaries in line with the Chicago traditional public schools, smaller class sizes and more special-education resources. It was the second strike by Chicago charter schoolteachers in recent months — an unusual event in the mostly nonunionized charter sector.

In Oakland, the school system has offered teachers a 5 percent raise over three years. But the union, the Oakland Education Association, is seeking a 12 percent boost over the same period and some of the same improvements that Los Angeles teachers demanded: smaller class sizes and more counselors and nurses in public schools.

Union leaders in Oakland can call a strike after Feb. 15 — about the same time that a neutral fact-finding committee is expected to release its conclusions regarding the labor negotiations.

A similar panel in Los Angeles released a report in late December and supported some of the union’s positions, but hopes for a settlement were dashed when teachers walked off the job in January.