Jack Amico, 23, part of Occupy Wall Street in New York City, attends "Occupy Congress," at sunset by the Capitol in Washington, Tuesday, Jan. 17, 2012. He brought this tear gas mask with him to be prepared, "I'm from New York and we're not used to police being so nice," he says. (AP Photo/Jacquelyn Martin)
Washington (CNN) -- The National Park Service plans to crack down Monday on what it calls "sleeping activity" at two longstanding camps established by Occupy DC demonstrators in the nation's capital.
The service notified protesters on Friday that they "may be subject to arrest and their property subject to seizure as evidence" if there are evident "camping violations" by around noon Monday.
The notice for those in McPherson Square and nearby Freedom Plaza said that to comply with the federal agency's camping regulations, demonstrators must remove all camping material from the sites and leave one side of all temporary structures open at all times. Authorities describe the purpose of the order as necessary to ensure public health and safety.
The demonstrators say they will defend their sites.
"Participants of Occupy DC at McPherson Square, both sleeping members and non-sleeping members, will defend the public space we have used as our center for activism on this Monday, January 30th," the group's website said. "Occupy DC will peacefully resist this politically motivated attempt to suppress the free speech of the disenfranchised 99%."
On Sunday, a small group of protesters met for about three hours under the statue of Civil War hero Maj. Gen. James McPherson, which is in the middle of the park, to discuss how to respond.
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A protester named Eli -- who would only give his first name, and who wasn't participating in the meeting -- said one of the ideas being mulled if Monday's deadline were imposed would be to hold a "sleep strike," in which demonstrators would play board games and do other things throughout the nights to avoid the "sleeping activities" banned by the Park Service.
"I plan on not leaving and not sleeping as long as possible," Eli said.
Also Sunday, video posted online showed a man appearing to walk away from U.S. Park Police members as he yelled out, "I have done nothing wrong." Two officers tried to grab him, before a third officer used a stun gun on the man, who was then handcuffed.
A CNN crew witnessed the arrest, which protesters said came after the man went from tent to tent removing notices posted by the park service.
Pastor Brian Merritt of Washington's Palisades Community Church said area churches have discussed helping house some of the protesters overnight so that they could continue a 24-hour vigil if park police began enforcing the rules against overnight encampments.
Rich Coffman, a Dallas resident who has been camping in the Washington park for three weeks, said demonstrators from Nashville and New York are expected to come Monday to show solidarity with the capital demonstrators.
Whatever happens with the camps and police, Caty McClure said it would not alter her and fellow demonstrators' commitment to their cause or their activism.
"The park and the occupation of the park is a tactic, it's not the movement," she said, calling the camps "a really important symbolic statement."
"If we can't sleep here, that does not end the movement."
Until now, the camps have been allowed to continue in Washington under a Park Service interpretation that considered the activity a "24-hour vigil."
Two weeks ago, National Park Service Director Jonathan Jarvis told CNN the "Occupy" demonstrators were behaving within their constitutional rights, and he saw no reason to end their encampments.
"We have the National Mall, McPherson Square, Freedom Plaza, all of those are First Amendment sites," he said, "and I think if there's any place in this country, Washington, D.C. is the place where we need to be the most tolerant of individuals that are exercising their First Amendment activities."
But California Republican Congressman Darrell Issa disagreed.
"Mr. Jarvis is completely out of line," said Issa. "It is not his job to interpret the Constitution, over law."
Issa, who last month wrote a letter to U.S. Interior Secretary Ken Salazar citing damage to part of a $400,000 renovation of McPherson Square, continued his criticism at a House hearing last week and came away unsatisfied with Park Service answers.
Occupy DC is part of a larger activist surge that began last year in New York and quickly spread. While the protesters have highlighted a number of causes, the overarching theme has remained largely the same: populist anger over what activists portray as an out-of-touch corporate, financial and political elite.
Demonstrators in Washington have been camping out in McPherson Square since the beginning of October. There was a daylong confrontation December 4 when protesters erected a wood structure overnight. It was eventually removed, after being deemed unsafe.