MARTELL, Neb. — With a sense of grim determination, a group of unlikely allies has begun gathering at kitchen tables, in churches and along fence rows here to plot what could be the final battle in the four-year conflict over the Keystone XL pipeline.

After months of quiet, a recent State Department report dismissing the ecological impact of the pipeline has cleared the way for a final decision on the plan for transporting oil extracted from the Alberta tar sands more than 1,700 miles to refineries on the Texas Gulf Coast.

An unusual coalition of environmentalists, property rights advocates and ranchers is now attempting to find new ways to derail a project that, more than ever, seems to be headed for approval in a nation eager for jobs and energy development.

“It’s been four very long, very difficult years,” said one of the opposition’s chief organizers, Jane Kleeb of Hastings.

But the group is buoyed by its success so far in stalling the project and in bringing so many disparate interests into the fight.

“I’m associated with people I never dreamed I would have been associated with,” said Randy Thompson, a Nebraska rancher and self-described conservative Republican, at a meeting of activists at his rural home south of Lincoln. “There’s a stigma on people considered environmentalists. I had that concept.”

The opposition effort is now focused on the new Secretary of State, John Kerry, who will make a recommendation to President Barack Obama on whether to green-light the project. .

Opponents and supporters will face off at public hearing in Nebraska, expected to be held in the spring.

Company officials with TransCanada, the pipeline builder, said they are confident they haave enough public support along the pipeline’s seven-state route, further bolstered by the favorable environmental impact report, to get clearance to begin.