A Washington-area labor organization poured $2.7 million into the fight for gambling expansion during the General Assembly's special session last month, according to its disclosure statement.

The total reported by the Washington Building & Construction Trades Council, an umbrella organization of labor unions, was far greater than any other company or organization that had reported its spending by midday Monday. The council's spending, done in the name of Building Trades for National Harbor, came in a winning cause as the legislature passed legislation putting the questions of whether to allow table games and a new Prince George's County casino on the November ballot.

The council is supporting an effort by MGM Resorts International to build a "destination" casino at National Harbor on the Potomac River -- a project it believes will generate thousands of high-paying construction jobs. Meanwhile the Peterson Cos., developer of National Harbor, disclosed that it had contributed $591,897 to Building Trades for National Harbor.

The requirement that groups and individuals disclose their spending on the special session was included in the casino legislation. The council's disclosure was part of a filing by its lobbyist, Mark Coles.

The council mounted an extensive television campaign for gambling expansion in June after a task force appointed by Gov. Martin O'Malley failed to forge a House-Senate consensus on the issue. The group attributed all of its spending to the media campaign and none to compensation for Coles.

Meanwhile, a group representing minority contractors in Prince George's County reported spending $289,317 on an ad campaign opposing the legislation. The Prince George's Contractors and Business Association trained its fire on MGM Resorts International, the prospective operator of a casino at National Harbor, but the group said its real dispute was with the Peterson Cos. over minority contracting at National Harbor.

A less obvious player was the National Gay and Lesbian Task Force Action Fund, which reported spending $346,938 on casino-issue lobbying -- not a topic on which it would be expected to have a firm position.

Rea Carey, executive director of the fund, said the spending was for a mailer urging lawmakers to oppose the bill in order to keep the issue of gambling off the November ballot. Carey said the group was concerned that  a gambling referendum could have an adverse impact on a separate ballot question involving same-sex marriage.

"There were concerns that having the gaming measure on the ballot could jeopardize the outcome of the marriage equality vote, which was the focus of the mailer," Carey said in a statement. "This has always simply been about ensuring that nothing gets in the way of securing marriage equality in Maryland."

Other lobbyists reported far more modest spending -- mostly for compensation for their services. Veteran lobbyist  D. Robert Enten received $30,000 from the Maryland Thoroughbred Horsemen's Association. Aaron Greenfield reported receiving $25,000 from MGM.

Peterson disclosed that its had paid Bruce C. Bereano $40,000 and Tim Perry $20,000 for their services.

The Cordish Cos., owner of the Maryland Live Casino at Arundel Mills, paid company officials David Cordish, Blake Cordish and Joseph Weinberg $5,000 each for their efforts. Somewhat more expensive were their paid lobbyists, Marta Harting, John Stierhoff and Brian Quinn, each of whom reported receiving $6,666 and change, and Carville Collins, $6,200. Earning the most from Cordish was J. Steve Wise, with $17,500.

The State Ethics Commission was accepting disclosure statements up until closing time Monday, and some of the documents may trickle in by mail over the next few days.

The lobbying disclosures are separate from those required for spending on the referendum campaign itself. Ballot committees must report contributions or expenditures of more than $10,000 to the State Board of Elections within 48 hours. As of last week, the campaign committee bankrolled by MGM had received $5.4 million to support the ballot question, while the group formed by Penn National Gaming to oppose it had collected $9.5 million.