Denver teachers and union representatives rally at the Colorado Capitol on Jan. 30, 2018, as a strike looms. (John Frank, The Colorado Sun)

Colorado’s second largest school district will cancel school on March 19 because so many teachers will be absent for a statewide teachers rally at the state Capitol building in Denver.

The 84,000-student Jeffco district made the announcement Wednesday, saying the number of expected teacher absences had exceeded the number that could be covered by substitutes.

In a letter to Jeffco families, district officials apologized for the inconvenience and said, “Please know we exhausted all resources before deciding to cancel school for students.”

District officials in Denver, the state’s largest district, said Wednesday they don’t have any “solid plans” in place to handle potentially large numbers of teacher absences on March 19, but hope to make a decision in the next few days. Leaders from the Adams 12 district, the state’s sixth largest, said they are monitoring teacher absences planned for the day of the rally and will give families advance notice if they have to cancel classes.

Three other large metro area districts — Aurora, Cherry Creek and Douglas County — will not be affected by the rally because they are off for spring break that week.

In 2018, several districts canceled classes or dismissed students early on three different days in April when Colorado teachers rallied at the Capitol.