ELKINS PARK Pennsylvania's largest teachers union has endorsed state Sen. Daylin Leach in the Democratic primary for the 13th Congressional District.

The Pennsylvania State Education Association and the National Education Association are backing Leach over three other Democrats vying for the seat being vacated by Rep. Allyson Y. Schwartz.

The district straddles southern Montgomery County and Northeast Philadelphia. In a poll this summer, education topped the list of concerns for Philadelphia voters.

PSEA, a multimillion-dollar political machine, has 5,600 members in the 13th District, Leach's campaign said in a news release Monday.

It was also Leach's No. 1 contributor in 2012, donating $27,500 for his Senate reelection campaign.

State Rep. Brendan Boyle, who is running against Leach, also received $11,300 from PSEA in 2012, and nearly five times that amount from Students First, a group that advocates for expanded school choice, including charter and magnet schools.

The other candidates are former Rep. Marjorie Margolies and physician Valerie Arkoosh.

- Jessica Parks