Protests are planned in 132 cities across the country June 30 to demonstrate outrage at the Trump administration’s policy of separating immigrant families at the border and detaining children apart from their parents.

Activists will descend on city centers, state capitols and, in Washington, at Lafayette Square across from the White House.

It wasn’t clear Tuesday how many people are expected to attend, although tens of thousands expressed interest on Facebook.

“We’re encouraging everyone who can possibly make it to D.C. to get there,” said Karthik Ganapathy, a spokesman and co-organizer of the demonstration. “The Trump administration is trying to dissuade people from coming to our southern border by administering this unimaginable cruelty to send a message. [Attorney General] Jeff Sessions has been clear about this. So we want to send a strong message and put pressure on the Trump administration to change this policy.”

A National Park Service spokesman said the agency received an application Monday to use Lafayette Park for a “free speech demonstration against immigration detention” on June 30. The application, filed by and local activist group D.C. Action Lab, estimates that 5,000 people will attend the rally.

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MoveOn, a progressive group that facilitates protests and petitions via its online organizing network, issued a call to action in response to Trump’s “zero-tolerance” immigration policy last week.

In the days since, the American Civil Liberties Union, the Leadership Conference, the National Domestic Workers Alliance, lawmakers and dozens of activist groups have signed on to help organize demonstrations and create Families Belong Together, an umbrella group for the coalition of activists involved.

“We are absolutely ready to have a mass mobilization,” Rep. Pramila Jayapal (D-Wash.) told Chris Hayes on his MSNBC show Tuesday morning. “We see the outrage, and we see that this has to be taken right to the White House, right to Donald Trump, to stop the family separations.”

Outrage over the Trump administration’s refusal to stop the practice of separating children — some still in diapers — from parents at the U.S.-Mexico border reached new heights Monday after images of children in chain-link cages and an audio recording of small Central American children desperately calling for their parents were circulated online.

The president has repeated his false claim that Democrats are to blame for the crisis. Congressional Democrats have called on the administration to simply reverse the “zero-tolerance” policy and return to the previous approach, under which families were not automatically charged with crimes and in some cases were released into the United States pending adjudication by immigration authorities.

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Trump also said parents illegally crossing the U.S.-Mexico border with their children “could be murderers and thieves and so much else.” On Tuesday, the president tweeted several more times on the matter, saying, “We must always arrest people coming into our country illegally.”

More than 2,300 children were taken from their parents at the border between May 5 and June 9, according to Department of Homeland Security statistics released Monday. In that period, the pace of family separations grew to nearly 70 per day.

MoveOn and other organizers of the June 30 demonstration said they hope the protest will attract people from various political backgrounds and walks of life.

“This isn’t about how you feel about campaign finance reform. This is about whether or not you think we should live in a nation where we tear children apart from their parents at the border, or if you believe we have to be better than this,” Ganapathy said. “This isn’t about progressive versus conservative. This is about what’s right.”

Although the format of the protest is still being decided, Ganapathy said it’s likely that organizers will opt for a stationary rally outside the White House rather than a moving march.