FORT KENT — Just hours after nurse Kaci Hickox defied state quarantine orders and went for a bike ride Thursday, Gov. Paul LePage vowed to use “the full extent of his authority allowable by law” to prevent her from having contact with the public.

LePage said in a written statement that state officials had been negotiating with Hickox’s lawyers to get her to abide by the 21-day quarantine, but that talks had broken down.

The standoff sets up the nation’s first legal test since ramifications of the Ebola outbreak were felt on American shores, pitting public health concerns against a person’s constitutional rights. It could have implications for thousands of health care workers now fighting the disease in West Africa and those who might volunteer to go in the future.

President Obama has said that health care workers fighting Ebola are heroes, but he didn’t mention Hickox or the disease during a 25-minute speech at a campaign rally for Democratic gubernatorial candidate Mike Michaud in Portland on Thursday night.

Maine health officials have criticized the leadership from Washington on the Ebola issue and have said other states are adopting more stringent guidelines for dealing with people who might have been exposed. But the LePage administration also backed off its demand for a mandatory in-house quarantine and on Thursday sought restrictions that mirror those recommended by the federal Centers for Disease Control and Prevention, which would let Hickox leave as long as she avoids public places where people gather.

Federal officials have said public health measures should be based on science, not fear, but maintain it is up to states to implement their own policies. Others have been more pointed in their criticism of Maine’s approach.

Dr. Lisa Ryan, president of the Maine Medical Association, and Dr. Lani Graham, former director of the Maine Bureau of Health’s Disease Control Division, issued a letter Thursday saying a mandatory quarantine is unnecessary and could dissuade people from volunteering in countries fighting the epidemic.

State officials have said repeatedly since Wednesday that they will seek a court order to enforce an in-home quarantine on Hickox, but there was no indication whether that had been attempted or what other form the governor’s exercise of authority could take. Calls to his press secretary were not returned Thursday.

Mary Mayhew, commissioner of the Department of Health and Human Services, said Wednesday that the state was in the process of filing the court order.

A spokesman for Attorney General Janet Mills would not say whether the state did seek a court order, noting that such orders are confidential.

“Maine statutes provide robust authority to the state to use legal measures to address threats to public health,” the governor said in his statement. The statement said the specific steps the state is taking could not be discussed because of confidentiality laws.

Hickox returned to the United States a week ago after treating Ebola patients in Sierra Leone for the aid organization Doctors Without Borders. She was immediately quarantined in New Jersey before she was released and returned to Maine. She has no symptoms and has twice tested negative for the virus, which has an incubation period of 21 days.

The federal CDC and several medical organizations, including the American Nurses Association-Maine and the New England Journal of Medicine, have said that the chances are remote that Ebola could be spread by a person who shows no symptoms. They noted that imposing mandatory quarantines on aid workers could hamper efforts to fight the disease in West Africa.

Maine officials, on the other hand, say they are responding to a public that is worried about a deadly disease that has killed about 5,000 people in West Africa.

LePage’s statement Thursday, indicating that the state had been negotiating with Hickox and her attorneys and would be amenable to guidelines similar to those recommended by the federal CDC, was a significant change from the state’s earlier stance.

On Monday, the day Hickox was released from New Jersey, Maine health officials announced they had more stringent protocols than those called for by the CDC.

“Maine will take further measures, out of an abundance of caution, to ensure public safety. … We will work collaboratively with the affected individual to establish quarantine of the individual in his or her home for 21 days after the last possible exposure to Ebola,” the Maine DHHS statement said.

The state later called for “an in-home quarantine protocol to ensure there is no direct contact with other Mainers until the period for potential infection has passed.”

The Maine CDC’s “in-home quarantine” guidelines now reflect the federal CDC recommendations for someone who is at “some risk” but shows no symptoms. The federal CDC does not call it a quarantine.

The federal guidelines call for direct active monitoring of a person who has treated Ebola patients, which means in-person visits to check on the person’s condition. A Maine CDC epidemiologist, someone who monitors and investigates disease risk in populations, visited Hickox’s home again Thursday and was inside for just a couple of minutes, presumably as part of the direct active monitoring.

The guidelines also can include – and in Maine do include – restrictions on the use of long-distance transportation like buses or airplanes, exclusion from public places like shopping centers and movie theaters, and staying away from work.

“These guidelines would allow an individual in the ‘some risk’ category to go for walks, runs or ride their bicycle, but would prevent such a person from going into public places or coming within 3 feet of other people in non-congregate gatherings,” the governor’s statement said.

The guidelines appear to be tailored for Hickox’s case.

“The governor remains willing to enter into such an agreement, on a case-by-case basis, with traveling health care workers who meet this definition,” Thursday’s news release said.

It is not clear whether the restrictions would apply to health care workers who treat people with Ebola in the United States.

Neither Hickox nor her lawyers has commented on the new protocols, though Hickox previously has said that she should still be able to engage in activities like going to the grocery store and interacting with friends.

“You know more than we do,” Hickox told a Portland Press Herald reporter at the door of her home Thursday afternoon when asked about possible compromises. “I’ve seen nothing in writing.”

Stephen Hyman, Hickox’s attorney, said Thursday that Hickox has every right to leave and the state has no legal authority to force her to stay in her house.

For his part, LePage appeared to be softening his stance on the mandatory quarantine. He told WGME in an interview, “I just want to protect Maine from that. That’s all. And if the court says not to worry, hey, don’t worry. I’m not going to go next to her.”

LePage said Hickox should submit to a blood test to see if she is positive for the virus.

When asked whether she would be amenable to taking a blood test, Hickox said, “We’ll decide that later.”

Hickox said she was tested twice during her New Jersey quarantine, and both times was negative for Ebola.

Part of the state’s reasoning for the quarantine, according to comments by Maine CDC Director Dr. Sheila Pinette on Tuesday, was that Hickox “may have been tested too early” in New Jersey, and that there was a chance that early tests would produce a false negative. She said the only way to be sure Hickox was free of the virus was to wait the full 21 days.

The American Civil Liberties Union of Maine issued a statement Thursday morning saying Hickox’s situation is not one in which public safety would justify limiting her civil liberties.

“In times like this, it is of utmost importance that the government remain transparent and even-handed and avoid overreaction,” said Alison Beyea, the group’s executive director. “Extreme measures like mandatory quarantines and police intervention raise serious concerns about government overreach, not to mention frighten the public.”

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