It's not surprising that the race for state House District 36 is dividing loyalties. Thanks to redistricting, the race is pitting two incumbent Democrats against each other: 10-term veteran Harry Readshaw faces first-year Rep Erin Molchany, whose 22nd district has been relocated. And if you want to understand the state of play here, just look at how the race has divided two teachers unions.

While the Pittsburgh Federation of Teachers has backed Molchany, the Pennsylvania State Education Association, which represents suburban districts across the state, has endorsed Readshaw. That's unusual: Both unions say they're usually on the same page when it comes to picking their champions. So why the split here?

PSEA Communications Manager David Broderick says his union's endorsement was guided by the "long relationship between PSEA and Rep. Readshaw. He's had a solid record on education issues, and he's spoken up many times on them." While Molchany is "a good candidate," Broderick says, Readshaw has "a long and distinguished record."

Over at the PFT, meanwhile, some portions of that record raised flags.

"Looking at the candidates' records is the first thing we do," says Jeremiah Dugan who chairs the PFT's political action committee. "And two things jumped out at us: We saw that he voted to authorize charter schools back in 1997, and that he had been a member of ALEC" -- the American Legislative Exchange Council.

ALEC has become a lightning rod for controversy as a corporate-backed group that drafts legislation for use in state legislatures. Many of the bills have a pronounced pro-corporate/anti-union bias, and ALEC has also drafted the kind of "Stand Your Ground" gun legislation that spawned outrage after the death of Trayvon Martin.

Readshaw's own ties to ALEC first attracted scrutiny in 2012, when the liberal group Keystone Progress alleged ties between ALEC and numerous state legislators. Campaign-finance records indicate that Readshaw made a $50 contribution to ALEC -- identified as "dues" -- back in 2001. But Readshaw denied ever being a member of the group, saying he "had no idea" what Keystone Progress was talking about when they called for him to step down.

ALEC keeps its membership rolls under wraps. But Bob Witmer, a spokesman for the Readshaw campaign, says the ALEC ties are "overblown" and that Readshaw was "never a card-carrying member" of the group. As for the charter-school vote, Witmer says that "a number of Democrats voted for charters back in 1997, not understanding the true ramifications of that until now." (Indeed, while the bill -- which became Act 22 of 1997 -- was opposed by many Dems, some did vote in favor of it. Among them: Allegheny County's Ron Cowell, then the ranking Dem on the House education committee.)

"If you're going to go back 17 years, you're going to find something you might not like" in a candidate's voting record, says Witmer. But more recently, he says, Readshaw has opposed Corbett budgets which failed to offset declining federal education dollars.

The PFT's Dugan acknowledges that Readshaw "hasn't been a Mike Turzai [the leader of House Republicans] on public education." (Though he notes that Readshaw has supported Republicans on some social issues like making English the state's official language. Such positions, Dugan says, also cast a shadow over Readshaw's bid for the endorsement.) But he contends that any tie to ALEC is a red flag, not least because "one of their agenda items was scrapping public pensions."

Dugan also stresses that Molchany, who sits on the House Education Committee, does more than just vote the PFT's issues. While he lauds Molchany's support of legislation that, for example, would preclude charter schools from using taxpayer money to advertise, "She has also been in many of the schools in our district to do outreach with students. She's been a strong and passionate supporter of teachers and public education."

Dugan surmises that PSEA is backing Readshaw partly because "They aren't big risk-takers." Most of the redrawn 36th district overlays Readshaw's old district, giving him home-field advantage. "But we look at the long-term -- on people's records and where we see the district moving. With [the election of City Councilors] Natalia Rudiak, Bruce Kraus and [Mayor] Bill Peduto, it's not the same district that it was a few years ago."

Of course, one could argue that for PFT, Molchany is the safe choice. She's got the backing of city officials like ... Rudiak, Kraus and Peduto. And if you're a city-based union, it might be unwise to buck a candidate preferred by the mayor -- especially one who is seems to be taking an active role in education issues. Dugan acknowledges that the union has an incentive to keep city officials in mind: "We've really tried to be a conduit between the city and the school district," partly because "without a strong city, it won't be a strong district." But that, he says, simply makes Molchany both a smart choice philosophically and pragmatically.

(Update: Should have noted this earlier, but I plumb forgot: Dugan himself, in fact, served as the Treasurer for Molchany's campaign until March 27 of this year, according to state records.)

To a large extent, the split education endorsements reflect broader divides within the race. The 36th district, after all, includes both city neighborhoods and older suburbs in the Brentwood and Baldwin-Whitehall school districts, where the PSEA represents teachers. Other unions have also split over the candidates. Molchany is getting support from unions like the PFT, Laborers, and SEIU -- all of whom have also backed "progressive" city candidates like Peduto. Readshaw, meanwhile, has earned the Allegheny County Labor Council's backing, as well as older-guard unions like the building trades.

The winner of this primary race, then, may be decided not just by how the district's lines were redrawn ... but by how much the political landscape itself has shifted.