Four years of mulling over the Keystone XL oil pipeline have apparently not been enough. In a little-noticed report Friday, President Obama indicated that he may again postpone any decision — this time until 2014.

It was the latest evidence that environmental groups are now winning the tug-of-war over the U.S.-Canada project. After months of reportedly being on the verge of approving it, Obama now appears to be pulling back.

An earlier self-imposed June decision deadline passed with no acknowledgement. The following month, Obama mocked the project's job creation prospects in a New York Times interview.

His comments contradicted his own administration's estimates and suggested that he was rejecting them in favor of statistics from environmental groups opposed to the pipeline.

"Republicans have said that this would be a big jobs generator. There is no evidence that that's true," Obama told the Times in July.

That's true only if you exclude the State Department's March report that Keystone would create 42,100 jobs, albeit mostly temporary ones. That Obama would ignore it does not bode well for the project's fans.

The latest snag involves complaints from progressive groups that a consultant firm hired by the State Department to report on the project's environmental impact has a conflict of interest because it has also consulted for pipeline companies.

The department's inspector general now wants to probe the matter. That will take until at least January, according to The Hill. It could result in a call for the environmental review process to be started over from the beginning.

The State Department isn't saying whether this will delay a forthcoming comprehensive report on the pipeline. But Obama has said he'll only OK the project if he is convinced by State, so he's unlikely to proceed with the probe unresolved.

By the way, there is no deadline for the State Department's comprehensive report.

Obama has been using such tactics since 2011 to delay a Keystone decision. Initially, he appeared to lean toward approving it: A State Department report that year was favorable and the project had strong backing from Big Labor and Big Business.

Yet Big Green environmental activists and their non-profit funders made opposing the pipeline a cause that year and succeeded in getting Obama to back down. In November 2011, he pushed back a decision until after the, ahem, 2012 election.

When congressional Republicans tried to force the issue in February 2012, Obama denied the project a permit and denounced the GOP's "rushed and arbitrary deadline."

Nevertheless, White House officials were careful to say then that project was not dead, merely delayed. An anonymous official later told Reuters in February that a decision would come in June.

Shortly after that, outlets like Politico were reporting that the administration was leaning towards approving it based on signs like the March State Department report.

Vice President Joe Biden lent credence to those rumors in May when he told a Sierra Club activist that he was opposed to project but "in the minority" among administration officials.

In a June environmental address at Georgetown University, Obama appeared to create wiggle room when he said he would approve it if the "net effects" do "not significantly exacerbate" pollution.

But at the same time, environmental groups were stepping up their campaigns. In February, the Sierra Club urged members to get "militant" and use civil disobedience tactics.

In a shrewd strategic move, they urged protests at Organizing for America offices, targeting the activist group spun off of the president's campaign organization. OFA had been conspicuously silent on the issue. The protests were a stark message to Democratic activists looking towards the next election.

And unfortunately for pipeline fans, there is always one more election on the horizon.