More than 150 advocacy groups sent a letter (pdf) to Congress on Thursday urging lawmakers to reject President Donald Trump's proposal to build a U.S.-Mexico border wall and spend the money on education instead.

Trump's "targeting of Muslims, refugees, and undocumented immigrants...are eroding the trust built by educators, parents, law enforcement, and communities over decades," the letter states.

Its signatories include the Center for Popular Democracy, SEIU, and the National Immigration Law Center, among other community groups and labor unions.

"Public schools are the cornerstone of our civic and economic infrastructure," it reads. "Their work is already complicated enough. Yet schools in low-income communities and in predominantly African-American and immigrant neighborhoods have struggled for too long with a lack of resources. Instead of separating families and building walls, we must invest in our schools as part of our nation's infrastructure. Stronger schools are schools where teachers have the tools they need to teach, students have access to a broad and rich curriculum, and families and students are welcomed, supported, engaged, and safe."

The letter described the experience of a teacher in Milwaukee whose second-grade student "crawled into her lap crying [and] told her, 'I am so scared that somebody is going to take my daddy away.'"

"These are the words of a six-year-old child, crying and afraid in school," the letter reads. "His teacher says, 'You can't teach like that. You can't learn like that.'"

An internal report from the Department of Homeland Security (DHS) seen by Reuters in February revealed that a border wall would cost $21.6 billion—roughly double what Trump himself has claimed, as Common Dreams noted.

A fight over the wall threatened a government shutdown this week, though that threat appears to have been sidelined amid the fight over healthcare.

The groups urged lawmakers to:

• Reject the White House's funding request for a 1,000-mile border wall along the U.S.-Mexico border, both now and in the future.
• Reject the $6 billion funding measure to triple the number of Immigration and Customs Enforcement agents for more raids and deportations.
• Reject Trump's proposal to slash federal education spending by $9 billion, which would eliminate federal funding for after-school programs, community schools, teacher training, and other critical supports.
• Invest in public schools, particularly those serving low-income African-American and Latino students.
• Say no to unaccountable voucher programs and charter school expansion.

"We unequivocally condemn this wall, and we unwaveringly denounce the politics of fear and division that have swept over this nation in the last 100 days," the letter states.

It was sent just ahead of a "Build Schools, Not Walls" action scheduled for May 1, or May Day, which is expected to see the largest nationwide mobilizations for immigration reform since 2006, when over a million people took to the streets in protest of raising penalties for undocumented immigration.

"Instead of funding President Trump's anti-immigrant agenda, we are seeking additional funding for our nation's public schools," said Keron Blair, director of the Alliance to Reclaim Our Schools, which spearheaded the letter. "Our kids deserve to go to neighborhood public schools that meet their social, emotional and health needs, making them well-rounded citizens in our global society. Now is the time for Congress to protect our students, fight for working families, and end the threat of mass deportations."