Environmentalists, Native American tribes and landowners vowed to continue fighting the contentious Keystone XL pipeline project Friday after President Donald Trump reversed the Obama administration and granted a key construction permit.

Opponents quickly outlined a multi-pronged battle plan calling for litigation, political pressure and demonstrations aimed at derailing construction of the project, intended to deliver more than 800,000 barrels of oil per day from Canada to Nebraska.

Pipeline owner TransCanada cleared a major regulatory hurdle with Friday’s Department of State permit allowing construction of the international project. But completion is far from a certainty, according to activists who spoke to reporters in a conference call.

A key remaining battle is a Nebraska government review that’s expected to take months. The project must also withstand court challenges. And heated protests, like those during TransCanada’s attempt to obtain government permission during the Obama administration, are likely to be rekindled.

“Game on,” said Bill McKibben, founder of 350.org. “The fight will be very intense.”

Pipeline backers claim the project will create jobs — though how many is disputed — and will deepen U.S. energy security. Opponents say the intensive process to extract crude from Canada’s tar sands region makes it particularly harmful to the environment, and ruptures would hold disastrous consequences.

Pressure public officials

Montana and South Dakota officials have previously approved the $8-billion pipeline to carry 830,000 barrels of oil per day through their states. But Nebraska’s five-member Public Service Commission must still decide whether to accept the route.

The commission’s approval is essential to TransCanada. It would enable the company to use eminent domain to acquire property from dozens of landowners who’ve refused to sell.

Bold Alliance President Jane Kleeb said she’ll encourage voters to express their disapproval of the pipeline to the four Republicans and one Democrat on the commission.

Keystone “is all risk and no reward,” Kleeb said. “We will be pressuring those commissioners to reject the pipeline.” Nebraska opponents say the pipeline could harm an important aquifer and the delicate sand hills region.

The terms for two of the commission’s members expire next year, possibly making them more susceptible to messages about Keystone XL. In a campaign for a commission seat in a liberal district around Lincoln, Kleeb predicted that an anti-pipeline challenger would challenge a Republican incumbent.

Nebraska Gov. Pete Ricketts (R), however, operates as a countervailing force. He said on Twitter that the Trump administration’s decision “is a welcome step forward” to bolster energy security and job creation.

Sue in court

Activists said they believe the State Department approved the pipeline permit by circumventing environmental laws and the rights of Native American tribes living in the three states along the route.

One problem, the Natural Resources Defense Council’s Anthony Swift pointed out, is that the State Department may have based its decision on an outdated study of the project. A fresh environmental review would have taken months to complete, but Trump ordered the State Department to make its decision within 60 days.

To meet the deadline, the State Department didn’t consider new evidence about the harmfulness of tar sands oil production, Swift said. The old data also overestimated the value of the oil, when the commodity was selling for more than $100 a barrel, while the recent price has been less than half that amount.

Obama rejected TransCanada’s application in 2015 after years of debate, saying it would diminish U.S. standing on global climate change. Nearby Native American tribes have also invoked legal claims against construction.

The Rosebud Sioux tribe of South Dakota contends the pipeline would violate treaty rights to an area that had been established in mid-1800s agreements with the federal government. That position is reminiscent of arguments made by the Standing Rock Sioux in their ongoing attempts to defeat the Dakota Access Pipeline.

Keystone XL also would run into lands claimed by the Ponca tribe of Nebraska.

“Our tribe has had limited to no consultation” with the Keystone builders, said Ponca Chairman Larry Wright. He described the pipeline as “the continued raping of our land and culture” and said he feared it would pollute what he described as “sacred” waters.

Take it to the streets

The renewed effort to to kill the Keystone XL will likely see public demonstrations to mobilize opponents. Demonstrations were hastily announced for Friday night in Washington, New York and other cities.

The Rosebud Sioux and other Sioux tribes may establish protest camps near the construction route, according to Indigenous Environmental Network organizer Dallas Goldtooth. The tribes “are willing to hold a physical space” and practice non-violent resistance, Goldtooth said.

A similar strategy helped galvanize public support for the Standing Rock Sioux against the Dakota Access Pipeline, but also led to repeated clashes with police and more than 700 arrests.

Follow the money

If pressure fails to sway government regulators and corporate bosses, opponents will target pipeline financial backers, said Michael Bruno, the Sierra Club’s executive director. Bruno said banks and other lenders may withhold funds to TransCanada if enough customers threaten boycotts.

“This project will not get built,” Brune said. “It’s one of the worst deals imaginable to the American people.”

Agreement between the two camps seems unlikely. TransCanada President and CEO Russ Girling said in a video Friday that he’d like to know more about opponents’ views, but made it clear he thinks the pipeline is positive.

“We will work closer with the communities to best understand what their concerns are,” Girling said. “But the fact that they understand North America needs energy, they need energy and the safest way to get energy is through a safe and modern pipeline.”