Oil and Gas Pipeline Construction vs. Massive Public Infrastructure Construction: Why do the Building Trades unions want the FORMER rather than the LATTER? I have no idea. [TITLE CORRECTED, 5/18 at 10:46 a.m.]

The AFL-CIO’s plans for a super PAC to take down Donald Trump ran into a big snag Monday, when one of the labor federation’s major affiliates objected to the involvement of billionaire climate activist Tom Steyer.

Sean McGarvey, president of the AFL-CIO-affiliated North America’s Building Trades Unions, co-signed a letter with seven other union presidents urging federation President Richard Trumka to cut ties with Steyer, a hedge fund manager who had spent money to aid environmental groups’ successful crusade to kill the Keystone XL oil pipeline. Building Trades had been a big supporter of the pipeline, in contrast with unions that sided with green groups’ opposition to the project.

The labor groups sent the letter less than a week after POLITICO revealed the impending launch of a new super PAC led by the AFL-CIO, Steyer’s NextGen Climate and three labor unions.

“We respectfully request that the AFL-CIO cut ties with Mr. Steyer and his political operation,” the letter said, “as we do not want any of our members’ financial support for the federation to be used against them and their economic well being in pursuit of this endeavor.”

The Obama administration’s rejection of the Keystone project riled the Building Trades when the president announced it last year. Laborers’ International Union of North America President Terry O’Sullivan, also a signatory of Monday’s letter, accused President Barack Obama at the time of “kowtowing to green-collar elitists.”

A major AFL-CIO affiliate called on the labor federation to end a new relationship with environmentalist billionaire Tom Steyer. Brian Mahoney and Anna Palmer, Politico, yesterday

This strikes me as a really easy rift to repair.  The Democrats—both presidential candidates and (I believe) most of their Senate and House candidates—strongly support massive public infrastructure projects, ranging from public transportation and bridge reconstruction projects to rehabbing or reconstructing inner-city public schools, to water system reconstruction projects in order to avoid further Flint, MI-type problems.

I’m certainly no expert on such matters, but it seems inconceivable to me that these major nationwide public infrastructure projects wouldn’t create far, far more building-trades jobs than oil and gas pipeline construction would, and do so in many more regions of the country.

So, what is it that I’m missing here?  Why isn’t this the quick, clear response by the AFL-CIO to this concern, to this demand by these Building Trades union presidents?  And to the anger of many of their rank-and-file members?  I don’t get it.