Is mayoral candidate David Catania reluctant to upset his supporters in the construction business? (Mary F. Calvert for The Washington Post)

Updated 7/21 with Baker comment and to note Catania has not taken campaign contributions from Baker and 7/22 to note LIUNA contributions to Bowser

With mayoral foe and fellow D.C. Council member David A. Catania hammering away at her record on education, affordable housing and more, Democratic nominee Muriel E. Bowser has generally shied away from meeting those attacks with attacks of her own.

But the tip of a wedge issue potentially favorable to Bowser may have surfaced last week, in the form of a seemingly innocuous letter from District lawmakers to the executive of a construction company that has been at odds with its workers and a prominent union.

Make that most District lawmakers: Catania was the only member of the council not to sign the July 14 letter to concrete construction firm Baker D.C. or send his own letter, as Council Chairman Phil Mendelson (D) did.

The letter asks Baker D.C., the local subsidiary of an Ohio-based national construction giant, to “meet and negotiate with workers” regarding a set of demands delivered in May and to “respect their legal rights to organize.” The Laborers’ International Union of North America has sought to organize the company’s workers, including by arranging a traffic-snarling May strike at a Connecticut Avenue NW construction site to push the company to the bargaining table.

Baker D.C. disputes the claims in the letter, including that its workers want to be unionized. Ken Fender, the company vice president to whom the council members addressed their missive, said LIUNA “tried to shut us down using outside agitators” to block entrances to the Connecticut Avenue site, “but in spite of this, the overwhelming majority of our co-workers came to work every day.”

“Baker pays fair wages and benefits to our co-workers and we will continue to do so,” Fender said. “We have been a good corporate citizen of the District and provide good jobs to DC residents.”

When union representatives recently canvassed the John A. Wilson Building for support from elected officials, including signatures on the letter, they made the point that Baker has done work on city-subsidized projects, including the Marriott Marquis hotel across from the Walter E. Washington Convention Center. “With the exception of Mr. Catania, every member of the Council signed a letter urging Baker D.C. to meet and negotiate with its employees and recognize their right to organize,”  D.J. Castro, business manager for the LIUNA local working with the Baker workers, said in a e-mailed statement.

So why didn’t Catania sign the letter?

Catania has had a long relationship with the construction industry, most prominently by working as a vice president for non-union electrical contractor M.C. Dean until 2012. While campaign finance records show he has not reported any donations from Baker, his political campaigns have enjoyed the support of firms active with Associated Builders and Contractors, a trade group that has opposed “project labor agreements” and other union-friendly measures, and as an independent — a former Republican, in fact — Catania has shown considerably less fealty to the city’s pro-labor political orthodoxy than most of his colleagues.

Brendan Williams-Kief, Catania’s council chief of staff, acknowledged that LIUNA had reached out to Catania about signing the letter but said he “didn’t have enough information about the situation at the time to sign.” Castro, in his statement, said the union “fully briefed each council office on the Baker D.C. workers and their fight for better pay, better benefits, and union recognition.”

If Bowser — like several other signatories, a beneficiary of Laborers campaign largesse — sees political gain in painting Catania as out of step with pro-labor values as he makes his pitch to Democratic voters, she is holding her fire for now. Asked about the letter, campaign spokesman Joaquin McPeek said in an e-mailed statement that it was “another example of Muriel Bowser standing with working families” and a testament to her “strong record of protecting the Democratic rights of the District’s middle class as a councilmember and looks forward to doing so as Mayor.” No mention of Catania.

Ben Young, Catania’s campaign manager, said voters “can’t read anything into” his boss’s decision not to sign the Baker D.C. letter. Young noted that Catania has sent similar letters in the past to other private firms subject to union organizing efforts — including health-care workers and security officers affiliated with the Service Employees International Union — though none of the previous letters Catania’s office provided dealt with construction firms.

“He does like to know what the facts are before he puts his name on there, and he just didn’t get a chance to do that,” Young said, adding that Catania “has a long record of advocating for the interests of all workers, union and non-union.”