The politically potent Montgomery County teachers union has endorsed County Executive Isiah Leggett for a third term, union officials announced Wednesday evening.

Candidates covet support from the 12,000-member Montgomery County Education Association because it gives them a spot on the union’s “Apple Ballot,” which is mailed to registered Democrats. Teachers also distribute the ballot at the polls on primary day.

The teachers union announcement rounds out a recent run of major endorsements for Leggett, including The Washington Post editorial board and Service Employees International Union Local 500, which represents several thousand school support staff.

The teachers’ endorsement is not a bolt from the blue. Leggett’s proposed 2015 budget calls for public schools to receive $26 million over the amount mandated by the state’s “maintenance of effort” law. Leggett’s spending plan last year did not propose exceeding state mandates.

Council member Phil Andrews (D-Rockville-Gaithersburg), one of Leggett’s two opponents in the June 24 Democratic primary, has consistently opposed budgets that exceed the mandated minimum. Leggett’s other challenger, Doug Duncan, funded teachers and schools generously during much of his previous tenure as county executive (1994-2006). But the union chose to stick with the incumbent, citing Leggett’s support for education during the lean recession years.

Isiah Leggett (Jeffrey MacMillan/Capital Business)

“Montgomery County has always had a deep bench of elected officials and candidates who are supportive of public education, and this year is no different,” union president Doug Prouty said in a statement.

“There was more than one candidate in this race with a proven record of supporting public education. But Ike’s commitment during very difficult budget years has made a real difference in maintaining the quality of our schools.”

Duncan has been endorsed by the Montgomery police and fire unions, Fraternal Order of Police Lodge 35 and the International Association of Firefighters Local 1664. The Montgomery County Green Democrats and the Montgomery County Volunteer Fire-Rescue Association have endorsed Andrews.