An umbrella group called Americans for Workplace Opportunity wants a vote on a bill passed by the Senate before the end of the year.

“We really see this as an important piece of unfinished business for LGBT workers and people around the country,” said Campbell Spencer, who is managing the campaign.

Human Rights Campaign has contributed $1.36 million to the campaign while Singer and Klarman have each put up $375,000 to pay for the effort. Spencer said that another major donor is expected to be announced in the near term.

Since November when the Senate passed the Employment Non-Discrimination Act, prospects of the House taking it up have been dim at best — Speaker John Boehner opposes it and Republican aides have said they believe existing laws already provide the protections.

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Spencer said the group’s goal is to demonstrate they have the 218 supporters needed for passage and then work with House GOP leadership to get it to the floor and passed. The group is already having a “tactical conversation about how best to move to passage,” according to Spencer.

Currently, the House bill has 202 co-sponsors. Only six Republicans are signed on as co-sponsors. Rep. Tom Reed (R-N.Y.) has also voiced his support of the measure.

But the campaign is already getting some traction from Colorado Republican Rep. Mike Coffman.

That Coffman is one of the first Republicans coming out in support of ENDA is no surprise, and it highlights another step in his political evolution. The Colorado Republican has reversed positions on immigration and abortion in recent months as he tries to fend off an challenge from Democrat Andrew Romanoff in Colorado’s competitive sixth district.

“I see this legislation as the workplace equivalent of the Golden Rule — do unto others, as you would have them do unto you,” Coffman said in a statement to POLITICO. “In the workplace, in 2014, we should judge employees the way we would want to be judged — based on our qualifications, our contributions and by our character, period.”

Americans for Workplace Opportunity played a major role in the Senate passage of the bill. It would be a significant victory for gay rights advocates on Capitol Hill if the House takes up the measure.

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Spencer said they are employing a similar grassroots and grass tops strategy.

“Our field campaign is the heart of our strategy and absolutely is what lead to the success in the Senate. We are duplicating it in the House,” Spencer said. “Each district has its own plan that’s tailored specifically to that member.”

The group has identified GOP Reps. Mario Diaz-Balart (Fla.), Mike Fitzpatrick (Pa.), Jim Gerlach (Pa.), Joe Heck (N.V.), Leonard Lance (N.J.), Frank LoBiondo (N.J.), Dave Reichert (Wash.) and Democratic Rep. Dan Lipinski (Ill.) as top tier targets to try and convince them to support the legislation.

The group has more than 30 field organizers on the ground in 17 states and has engaged eight Republican-leaning public affairs firms. Over the past month, the campaign has driven more than 1,000 calls to members district offices, sent post cards and held several district meetings. And, they have plans in the coming weeks to hold more than 100 volunteer engagement events, including 56 canvassing events, 43 phone bank events and 14 other events and community meetings in priority districts.

In addition to Spencer, who previously served as in the Obama administration, public relations firm Granite Integrated Strategies’ Kristen Hawn and Ali Harden have been brought on to assist with media strategy.

Other groups involved in the group include Log Cabin Republicans, AFSCME, ACLU and the SEIU.