South Portland officials are preparing for a legal battle with members of the oil industry over a City Council vote Monday to block the export of tar sands oil from its port – an action that environmentalists say could set a precedent for communities across the continent that don’t want the Canadian crude flowing through.

National conservation leaders praised the city Tuesday for leading the charge against tar sands oil and showing that organized citizens can defeat the global oil industry.

“You’ve dealt a huge blow on behalf of the planet’s atmosphere,” said Bill McKibben, founder of 350.org, an international organization dedicated to preventing climate change. McKibben was part of a teleconference with the city’s mayor, local advocates and the media.

Mayor Jerry Jalbert said Tuesday that he and City Manager James Gailey have been conferring with the city’s legal counsel to prepare for an anticipated lawsuit over the vote. The city may solicit donations from U.S. and Canadian environmental groups to cover the legal costs of defending the ban without burdening taxpayers.

“I think they’ll find wide support,” McKibben said of the city’s potential legal fund.

Opponents of the zoning ordinance adopted Monday have said they plan to either sue the city or ask voters to overturn the regulations, which prohibit the bulk loading of crude oil onto marine vessels and the construction of facilities for that purpose.

Oil industry groups dispute claims by environmentalists that tar sands oil is any more likely to spill or is more harmful to people’s health than other types of oil that have been flowing through a South Portland-to-Canada pipeline for decades. The ordinance, they say, will hurt the state’s economy by sending a negative message to businesses, eliminating future options for longtime employers and preventing job growth.

“(We) will evaluate all political and legal means available to overturn this ordinance,” said Jamie Py of the Maine Energy Marketers Association, who is spokesman for The Working Waterfront Coalition, a group of oil industry representatives and local business owners.

Tom Hardison, vice president of Portland Pipe Line Corp., which operates the underground oil pipeline from South Portland to Montreal, said the company is considering “several options” for responding to the city’s decision, which he called biased and slanted. The concerns that Portland Pipe Line might use its pipeline to export tar sands oil led the city to ban all crude export operations.

Jim Merrill, a spokesman for Portland Pipe Line, would not say Tuesday whether the company had made a decision about its response to the city’s vote.

To hold a referendum on the ordinance, opponents would have to gather 950 signatures in the next 19 days. No one had taken out petition papers from the South Portland city clerk’s office by the close of business Tuesday.

Jalbert said he thinks “it might be difficult just to get the signatures” because of residents’ “fatigue from this whole issue.”

A referendum attempt also could be risky. The opponents spent hundreds of thousands of dollars to support a referendum last fall against a broader anti-tar sands ordinance, and won by 200 votes. The latest ordinance appears to have broader support based on the 6-1 backing of the City Council.

Ivy Frignoca, an attorney at the Conservation Law Foundation in Portland, said she expects opponents to file a lawsuit because the type of regulations enacted haven’t been challenged before.

“This is really a precedent-setting ordinance,” she said.

A lawsuit by opponents is likely to argue that the city overstepped its authority, such as regulation of trade, in violation of the U.S. Constitution’s Commerce Clause or the state’s Home Rule act. Frignoca said city officials worked hard to make sure the ordinance didn’t do that.

“It was very carefully crafted to withstand legal challenge,” she said.

Py, the Working Waterfront Coalition spokesman, told The Associated Press on Tuesday that it was “a dangerous precedent to have a small minority of people control interstate commerce,” and said the coalition is considering suing the city on constitutional grounds.

With the potential lawsuit looming, the governor’s energy chief said Tuesday that the state is reviewing South Portland’s action and he wants to be part of the conversation about the flow of petroleum products through Maine, the AP reported.

Patrick Woodcock, director of the Governor’s Energy Office, said he hopes the city and state officials can look at the big picture when it comes to the North American energy boom.

“What I would hope is that we can step up and think about managing this transformation in a way that works for our economy and also works for our environment,” he said.

South Portland’s vote made news and was shared on social media across the U.S. and Canada, in communities where activists also are hoping to do their part to block the export of tar sands oil.

The heavy oil is mixed with sand and requires additional energy to extract, process and refine. Environmentalists have said Canada’s export of tar sands oil from its vast reserves would mean “game over” in efforts to prevent a disruptive shift in the global climate. The oil industry argues those concerns are overblown.

Communities in the U.S. and Canada where tar sands oil has been a heated topic will continue watching the fallout of South Portland’s decision. But some of them took Tuesday to celebrate.

Jane Kleeb, director of Bold Nebraska, a group opposing the planned Keystone XL Pipeline to carry the oil to Texas, said the City Council’s decision shows oil companies that “their projects are not inevitable when they face independent communities.”

Meanwhile, some other residents along the pipeline from Montreal to South Portland also celebrated the action.

Montreal environmental activist Steven Guilbeault told the CBC network that he was pleased with the decision. “I think it’s good news for Montreal. I think it means that there are less chances we will be receiving tar sands here,” he said.

Mary-Jane Ferrier of Protect South Portland, the citizens group that organized in support of the ordinance, said she heard Tuesday that residents in Saint-Cesaire, Quebec, which is on the pipeline’s route, “were thrilled to hear the news.”

Ferrier and about a dozen South Portland residents and environmentalists gathered Tuesday morning on the Maine State Pier in Portland to send the message that they wouldn’t back down from whatever challenge is to come.

“We’re not going away,” Ferrier said.