Open borders activists and celebrities are going on a 24-day hunger strike to protest the Trump administration’s “zero-tolerance” policy on illegal immigration at the southern border.

The hunger strike, organized in part by the Robert F. Kennedy Human Rights organization, kicked off on Saturday blocks away from a federal courthouse in McAllen, Texas, where illegal immigrants detained for unlawfully crossing the U.S. border are sent to be prosecuted.

“Today, we have a president who has a different idea of what it means to be an American,” Kerry Kennedy, who runs the RFK center and is one of the strike’s organizers, told USA Today after visiting the courthouse Friday.

The planned duration of the strike is 24 days to represent the estimated 2,400 children separated from their parents who were detained and referred for prosecution for illegally crossing the border.

Although the event is billed as a 24 day-hunger strike, most participants would not be fasting for more than 24 hours at a time. Other hunger strikes, such as one that a Cuban dissident conducted several years ago to protest the lack of freedom of expression in Cuba, have lasted up to 135 days.

The event also has backing from several celebrities and left-wing politicians, including Martin Sheen, Levar Burton, Alec Baldwin, 10 House members and one senator, according to USA Today.

The Justice Department announced the implementation of its “zero-tolerance” policy on illegal immigration in April to reduce the number of illegal crossings over the U.S. southern border.

Trump signed an executive order on Wednesday halting the practice of separating illegal migrant families at the border and instructing the Department of Homeland Security to detain illegal migrant families together until their cases are processed in court.