Protesters hold arm bands in silent protest during a U.S. State Department meeting to discuss the proposed route of the Keystone Pipeline in Grand Island, Neb., April 18. (Dave Weaver/Reuters)

Increasingly polarized as the bitter fight over the Keystone XL pipeline drags on, backers and opponents of the 1,700-mile project met in the same place Thursday for the only federal public hearing scheduled before the Obama administration decides whether to allow its construction.

The gulf between them was larger than the ice-and-snow-covered Heartland Events Center, the state fairgrounds and arena complex where nearly 1,000 people braved a late April snowstorm to testify to State Department officials. Even the smallest points were hotly contested throughout the all-day hearing and in dueling news conferences that preceded it.

But there is no missing the huge stakes in the $5.3 billion pipeline for TransCanada, the company that wants to send as much as 830,000 barrels of diluted bitumen oil each day from Alberta’s oil sands to U.S. refineries in the Gulf of Mexico, or for environmentalists, who are making a stand over climate change, aquifer safety and other issues. Labor, which hopes to gain 3,900 pipeline construction jobs, and landowners, who were on both sides of the issue Thursday, were also well represented.

The Obama administration wants to reduce U.S. reliance on oil from the Middle East and elsewhere without alienating environmentalists or creating friction with the Canadian government, which supports the project.

That may be difficult. “When your bulldozers try to cross our line in the state of Nebraska, every single person will be there to say ‘ No!,’ ” Jane Kleeb, director of Bold Nebraska and a leader of the opposition, testified. Hundreds of opponents wearing black “Pipeline Fighter” armbands cheered her wildly.

But Brigham McCown, a former acting head of the Pipeline and Hazardous Materials Safety Administration, and now a consultant to pipeline backers, said 2.6 million miles of pipeline are currently moving energy, chemicals and water safely around the United States. About 13.5 billion barrels of oil were transported in 2012, McCown said, far more safely than by any other method.

Secretary of State John F. Kerry must decide whether the pipeline is in the United States’ national interest. The department held the hearing because the pipeline will cross a U.S. border and already has received more than 800,000 comments, said Kerri-Ann Jones, assistant secretary of the department’s Bureau of Oceans and International Environmental and Scientific Affairs. Jones said all comments received by April 22 will be posted online.

The State Department must consult with eight other federal agencies before issuing its recommendation, she said.

The administration rejected the project once before, in 2012, but said it was because an arbitrary deadline set by Republicans in Congress prevented the State Department from gathering all the needed information. Landowners have also sued over whether Nebraska Gov. Dave Heineman had authority to approve it.

TransCanada said it will construct one of the safest pipelines ever built, with special precautions that include more deeply buried pipe monitored from a 24-hour center where any section of the line can be shut off within 15 minutes. Opponents noted again that even a revised route that would move the pipeline away from Nebraska’s sensitive Sand Hills region still takes it through a portion of the giant Ogallala aquifer, one of world’s largest underground sources of fresh water, which stretches from South Dakota to Texas.

They pointed to the pipeline rupture three weeks ago that sent 5,000 barrels of the same kind of crude oil into a residential neighborhood in Mayflower, Ark., and a much larger spill that polluted the Kalamazoo River in 2010.

Residents of both areas spoke passionately about the damage. “Thirty-two months have passed, and we’re still dealing with cleanup; we’re still dealing with dredging,” said Susan M. Connolly of Marshall, Mich., who became an activist after the Kalamazoo spill. “It’s never going to go away.”

The two sides at Thursday’s hearing do not agree on whether the Canadians will simply find another way to take the oil to refineries elsewhere if Keystone XL is rejected. Environmentalists contend that without the pipeline’s capacity, oil companies will greatly slow production.

They also say that the process by which the thick oil sands crude is brought out of the ground, which is akin to strip mining, releases more greenhouse gases than other forms of oil drilling, and that the thick, coarse oil will corrode the pipeline more quickly than other forms of crude.

TransCanada officials said the latter point is simply untrue, and Corey Goulet, vice president of the Keystone project, noted that the petroleum products are still necessary in modern society to “fuel vehicles and airplanes that brought everyone here today, including project opponents.”