Melania Trump, the first lady, also appeared to question the treatment of migrants. For all five women to speak out against the same policy, with some crossing party lines in doing so, highlights the mounting bipartisan backlash against the practice.
Speaking at an awards lunch for the Women's Forum of New York, Clinton said what was happening to families at the U.S. -Mexico border is "horrific".
Michelle Obama made her thoughts on the zero tolerance policy known by sharing Bush's op-ed, simply writing "Sometimes truth transcends party".
She added the United States government "should not be in the business of warehousing children in converted box stores or making plans to place them in tent cities in the desert outside of El Paso".
USA first lady Michelle Obama, right, and former US first lady Laura Bush laugh as they participate in an African First Ladies Summit in Dar es Salaam, Tanzania, July 2, 2013.
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"It so challenges the conscience of our country that it must be changed and must be changed immediately", she said during a news conference at a San Diego terminal that is connected to the airport in Tijuana, Mexico by a bridge. "I've studied the Bible, both the Old and the New Testament". "What is being done using the name of religion is contrary to everything I have ever been taught". Even the current first lady joined the fray over the weekend. Inconsolable children calling for their parents can be heard in the audio obtained by ProPublica.
The continuation of Deferred Action for Childhood Arrivals - the Obama-era program that defers deportation for some people brought to the country illegally as children - is an issue that every group can agree on, with 8-in-10 saying the United States should continue the policy that Trump has sought to end and allow immigrants who meet the qualifications to remain in the US.
"She believes we need to be a country that follows all laws, but also a country that governs with heart", her spokeswoman Stephanie Grisham told CNN.
Demonstrators gather outside the Massachusetts State House in Boston to protest against the Trump administration policy.
Almost 2,000 children have already been removed from their families as a result of the administration's policy, and hundreds more are being pried away each week.
Mr Trump plans to meet with House Republicans on Tuesday to discuss pending immigration legislation amid an election-season debate over an issue that helped vault the NY real estate mogul into the Oval Office in 2016. "That's their law." - remarks to reporters Friday.