LINCOLN, Neb. (Reuters) - Opponents of the Keystone XL pipeline vowed on Thursday to block construction of the controversial project if Nebraska regulators approve the proposed route later this year.

FILE PHOTO: Various anti-pipeline signs line the walls of the machine shed of Art and Helen Tanderup, who are against the proposed Keystone XL Pipeline that would cut through the farm where they live near Neligh, Nebraska, U.S. April 12, 2017. REUTERS/Lane Hickenbottom

The state's regulators wrapped up a final public hearing a day early on Thursday on TransCanada Corp's TRP.TO proposed Keystone XL pipeline after four days of contentious exchanges between lawyers. Nebraska's Public Service Commission will make its final decision by Nov. 23.

After the hearing, two dozen landowners and other pipeline opponents vowed non-violent civil disobedience if the commission rules in favor of TransCanada. The action, they said, would be similar to months-long protests in North Dakota led by the Standing Rock Sioux tribe against the Dakota Access pipeline.

“Standing Rock was a dress rehearsal compared to what this will be,” said Jane Kleeb, chair of Nebraska’s Democratic party and founder of the Bold Alliance anti-pipeline group, her voice cracking. “We are not going to let an inch of foreign steel touch Nebraska soil.”

The proposed 1,179-mile (1,897-km) pipeline, linking Canada’s Alberta oil sands to U.S. refineries, has been a lightning rod of controversy for nearly a decade.

The project has pitted landowners and environmentalists worried about greenhouse gas emissions, oil spills and environmental contamination, against business advocates who say it will lower fuel prices, shore up national security and bring jobs.

Lawyers representing about 90 landowners opposed to the pipeline that would traverse their farms and lawyers for TransCanada sparred over the four days of the court-like hearing, held in a hotel ballroom and presided over by a retired judge.

There was heavy security at the hearing, which was open to the public.

Intervenors in the hearing ranged from the landowners - mainly ranchers and farmers - to native American tribes and TransCanada representatives. Each group made its case to the five elected members of the Public Service Commission about whether or not the proposed pipeline was in the “public interest.”

David Domina, Omaha-based attorney for the landowners, said TransCanada failed to do that.

“TransCanada … put on their best case,” he said. “I should think Nebraskans would be disappointed in their best case. I don’t think they sustained their burden of proof,” he said.

Just recently, TransCanada officials said they would only decide in December whether to proceed with the project after gauging demand from oil shippers and awaiting a decision from Nebraska’s Public Service Commission.

Nebraska Governor Pete Ricketts, who was on a five-day mission to Canada this week, said he was optimistic the commission will approve Keystone XL, calling it “the safest pipeline ever built.”Canadian pipeline export capacity is currently about 4 million barrels per day, and producers are matching that with 4 million barrels per day of export-ready output, according to the Canadian Association of Petroleum Producers, an industry group.

The group said oil supply available for export is expected to grow to 5.5 million barrels per day by 2030, and the industry wants more pipeline to accommodate it.

But since Keystone XL's rejection by the previous U.S. administration, alternatives have come into play, such as Kinder Morgan's KMI.N Trans Mountain pipeline and Enbridge's ENB.TO Line 3.

TransCanada spokesman Matthew John said after the hearing that the company has “very good support from our core customers, and the goal … for this project is to obtain a significant amount of 20-year, long-term contracts.

“And we are making very good progress on that and we’re absolutely committed to making this project a reality,” he said.

John said TransCanada was “hopeful for a positive outcome” from the Nebraska commission.

“The safety (and) the environmental merits of this project have been studied at length. And the preferred route is the route that has been determined to be the safest and most environmentally responsible route,” he said.