Despite political rifts, the labor-green alliance has never been stronger.

It sounded like a potent combination: unions and other progressive groups teaming up to form a new Super PAC aimed at defeating Donald Trump. The PAC, called For Our Future, was organized by four major labor groups including the AFL-CIO, and hoped to raise $50 million for voter-turnout efforts. Environmental activist Tom Steyer, who’d reportedly been discussing a collaboration with the AFL-CIO for months, announced he would give $5 million to the group.

Then the New York Times published a pair of letters sent to AFL-CIO president Richard Trumka by the presidents of seven construction unions who were “enraged” by Steyer’s participation: The unions would not support the PAC and asked the AFL-CIO to sever its ties to Steyer.

The letters amount to more of a public airing of pre-existing, internal disagreements than evidence of a green-labor split. As the partnership with Steyer indicates, labor groups and environmentalists are finding more common ground than ever – leaving unions allied with the fossil-fuel industry increasingly isolated.

The letter from the building trades organizations warns that the AFL-CIO has been “infiltrated by financial and political interests.” Those same unions, however, have nurtured their own relationships with special interests – notably the American Petroleum Institute, the largest trade association for the oil and gas industry. Letter signatory Sean McGarvey, the president of the AFL-CIO’s Building and Construction Trades Department, also co-chairs the Oil and Natural Gas Industry Labor-Management Committee, which he describes as “a unique partnership between America’s building trades unions and the American Petroleum Institute.” The partnership was founded in 2009 to promote domestic oil and gas production. As of 2012, the API had poured over $2.6 million into the group, with at least another $85,000 going directly to AFL-CIO’s Building and Construction Trades Department.

The alliance was on full display in the public debate over the Keystone XL pipeline, which both API and the union supported. Steyer was on the other side; he used his influence as a major Democratic donor to elevate an unlikely campaign against the pipeline into a high-profile political battle. The construction unions have not forgiven the billionaire for helping to squash a project they saw as a source of jobs.

But the Keystone XL pipeline is not the whole story. Several of the unions who’ve objected to cooperation with Steyer have already endorsed Hillary Clinton, who announced her opposition to Keystone last year.

That the AFL-CIO was willing to partner with Steyer at all is a sign that the gulf between labor and the climate movement is narrower than it once was. The federation has called Obama’s Clean Power Plan a “historic step,” and in December, the federation issued a statement of support for the climate agreement reached in Paris.

Even many of the same unions who’ve balked at the idea of working with Steyer are taking advantage of jobs in the renewable energy sector. The United Association of Plumbers, Fitters, Welders, and Service Technicians describes the “green” sector as “one of the fastest-growing sectors in our industry right now.”

ZOË CARPENTER is an editor for The Nation.