BILLINGS, Mont. (AP) — Environmentalists asked a federal judge on Monday to cancel approvals issued by the U.S. Army Corps of Engineers for the Keystone XL oil pipeline from Canada, opening another front in the legal fight over a long-delayed energy project that President Donald Trump has tried to push through to completion.

Attorneys for the Northern Plains Resource Council, Sierra Club and other groups filed the latest lawsuit against the $8 billion tar sands pipeline in Montana, where they’ve previously won favorable rulings in related cases.

First proposed in 2008, Keystone XL was rejected by President Barack Obama and revived under Trump. An appeals court last month lifted an injunction that had blocked the project. That came after Trump issued a new permit, in a bid to nullify a legal challenge to the pipeline by canceling its previous permit.

A separate lawsuit challenging Trump’s actions on the permit is pending in federal court. Monday’s lawsuit gives pipeline opponents another avenue to delay or stop it should Trump’s permit be upheld.

The environmentalists claim that the corps did not examine the potential for oil spills and other environmental damage when it approved plans submitted by pipeline developer TC Energy. The line would cross hundreds of waterways along a 1,184-mile path from Canada to Nebraska.

Almost all the crossings fall under a Corps of Engineers program that gives blanket approval to individual pieces of a bigger project without considering the potential cumulative effects, according to the lawsuit. That means no analysis was done of the possibility that the line would break and cause an oil spill or of its potential contributions to climate change, the lawsuit says.

The corps declined to comment Monday.

Montana Gov. Steve Bullock on Monday criticized the Trump administration for approving the pipeline without consulting more with the Native Americans whose land it would pass through, but he said he is open to supporting the project itself. “I’ve said from the beginning that, look, if it’s done right we can’t take it off the table,” Bullock said during an online meeting about climate change.

TC Energy, until recently known as TransCanada, said prior to the injunction being lifted that it was too late in the construction season to begin work this year.

In yet another attempt to thwart the project, the environmental groups behind Monday’s lawsuit also filed notice that they intend to sue Trump over the pipeline’s potential harm to imperiled species. They say building the line would kill birds such as the whooping crane and piping plover and an endangered fish, the pallid sturgeon.

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