With just days left to submit public comments on a National Park Service proposal to alter how protests are handled in the District, civil rights advocates have issued urgent calls to oppose the measures, saying they would violate First Amendment rights.

The proposal, which was introduced in August, floats more than a dozen changes to how the Park Service facilitates protests, including how many demonstrators may gather on national parks’ land without a permit, what areas protesters can demonstrate in, and whether protesters should be required to reimburse the agency for the support and security it provides.

Constitutional experts immediately cast doubt on whether imposing fees on groups exercising their First Amendment rights would pass constitutional muster, and protest organizers said having to pay fees would discourage people from demonstrating.

Lawyers with the American Civil Liberties Union are scrutinizing other parts of the proposal, including limits on where protesters can stand on the sidewalk outside the White House. The organization issued a public response to the Park Service that includes a point-by-point takedown of the proposals.

“The heart of the matter is clear: President Trump might not like having protesters on his doorstep, but the First Amendment guarantees their right to be there,” Arthur Spitzer, legal co-director of the American Civil Liberties Union of D.C., wrote in a blog post Tuesday explaining the organization’s opposition.

“Fee requirements could make mass protests like Martin Luther King Jr.’s historic 1963 March on Washington and its ‘I have a dream’ speech too expensive to happen.”

As of Friday, three days before the public comment period comes to a close, more than 10,000 people had voiced their opinions on the rule changes. Nearly 15,000 had signed an ACLU petition opposing the restrictions.

Among the proposed rules that have invited the most ire is a recommendation that the Park Service limit the area outside the White House where protesters may gather. The proposal suggests that the agency close 20 feet of the 25-foot-wide sidewalk beyond the White House gate on Pennsylvania Avenue NW.

The ACLU has previously sued the federal government, and won, over attempts to limit areas in which protesters could gather near the White House.

Several activists, including Ben Wikler, the Washington director for MoveOn.org, said the Trump administration was trying to “curtail protests” and push demonstrators away from the White House fence.

But the Park Service cited concern about the degradation of historic sites, monuments and turf as reasons for limiting the number of protesters in certain areas.

The agency has not produced an estimate for how much money it spends annually to support protests and rallies, but spokesman Mike Litterst said that, on average, the processing of permits alone costs the Park Service $700,000 in staff time per year.

The number of protests in Washington has increased substantially to an average of 750 per year, and they are growing in size as well. Last year, the District had 714 permitted demonstrations, including the Women’s March, in which tens of thousands packed the Mall and city streets.

So far this year, the Park Service has helped coordinate hundreds of protests, including the sweeping March for Our Lives, the Families Belong Together rally and the Unite the Right white-nationalist demonstration, which drew thousands of counterprotesters and required intricate security plans and officers from multiple agencies.

It’s put a substantial strain on the agency and its budget, which has not grown to accommodate the rising tide of civil unrest, Litterst said.

“Those costs can very quickly get up into six figures,” he said. “We don’t get a supplemental budget. No one says, ‘Oh, First Amendment events at the National Mall have really gone up, so here’s an increase to your base budget to support that kind of thing.’ ”

Organizers who want to host large demonstrations in District parks are already required to cover certain costs, including providing toilets, on-site emergency medics, setup and takedown services, and more, according to protest organizers.

“According to the new proposal, the park service is considering charging demonstrators for things like ‘sanitation and trash removal’ and ‘harm to turf,’ ” the ACLU’s Spitzer wrote. “But of course, the park service does not plan to charge the 45 million non-demonstrators who visit the National Mall every year for the fencing and sanitation their presence requires or for the harm to the turf that they cause.”

The public comment period for the 14 proposed changes closes Monday.