The Keystone XL Pipeline project has been endorsed by numerous unions, including those representing laborers, builders, pipefitters, electrical workers and the building trades. With the country still hurting from the recession, they are eager to get in on the estimated 20,000 jobs the project will create.

"There is no reason for any further delay," America's Building Trades Unions President Sean McGarvey said last month. "Thousands of American skilled craft professionals are ready to get to work now."

But those union members have to wonder why the top leaders in organized labor, with all of their influence in the Obama White House, still refuse to go to bat for the project. At its annual meeting in Florida on Tuesday, the AFL-CIO declined to officially back Keystone, even though it promises to create far more union jobs than anything President Obama has done in four years.

Instead of the AFL-CIO's endorsement, the project's backers had to settle for a vague statement of general support for "the expansion of our pipeline infrastructure." The statement followed three paragraphs about addressing climate change and promoting renewable energy. Union members can be forgiven for wondering why, even within their own organization, their interests take a back seat to those of wealthy, white urban environmentalists.

Keystone should be an easy call for the AFL-CIO, especially for a movement that is rapidly losing members, jobs and clout. The Labor Department reported last month that only 11.3 percent of American workers belong to unions, down a half point from last year and the lowest since the government has tracked the figure.

One of the projects of the top union leaders in recent years has been to align themselves with environmental leaders. The theory here was that promoting "green jobs" projects would be a bonanza for the unions.

They formed a coalition called the BlueGreen Alliance with the Sierra Club and the Natural Resources Defense Council and were successful in getting the administration to shell out billions in taxpayer dollars on wind and solar projects. But the five million jobs Obama promised never materialized. Instead, funding recipients such as Solyndra, Abound Solar and A123 went bankrupt.

As part of its deal with Big Green, the AFL-CIO has apparently decided to sit on its hands over the $7 billion U.S.-Canada pipeline project.

Laborers International Union of North America President Terry O'Sullivan denounced the alliance last year: "We're repulsed by some of our supposed brothers and sisters lining up with job killers like the Sierra Club and the Natural Resources Defense Council to destroy the lives of working men and women."

AFL-CIO President Richard Trumka told The Washington Examiner last year that the project could occur in a second Obama term -- if the environmentalist groups' concerns were addressed.

"A lot of people try to say it is either/or. Either you do the project or you destroy the environment. I think there is a way to do things both ways. Where you can do things without destroying the environment," he said.

But such efforts have failed to placate Big Green. Last month, Nebraska's governor Dave Heineman, R, approved a new route for the pipeline, moving it away from reservoir aquifers that the environmentalist groups warned could be affected by a potential leak. The Sierra Club responded by issuing threats to the Obama administration, urging its members to get "militant" and engage in civil disobedience to stop it. In other words, the aquifer issue was just a pretext for blanket opposition to fossil fuel development.

So far, the White House has repeatedly chosen the environmentalists over unions on this issue, and any final decision is delayed until at least June. It is a lot easier for them when the top leadership in Big Labor wasn't making it a priority.