Former Florida Gov. Jeb Bush on Monday called on President Donald Trump to end the “heartless policy” of separating parents and children who cross the U.S. border illegally. “Children shouldn’t be used as a negotiating tool. @realDonaldTrump should end this heartless policy and Congress should get an immigration deal done that provides for asylum reform, border security and a path to citizenship for Dreamers,” Bush wrote in a tweet replying to Trump. Story Continued Below People on both sides of the aisle have denounced the Trump administration’s policy, including Bush’s sister-in-law, former first lady Laura Bush, who wrote an op-ed in The Washington Post denouncing the practice of separating families. Trump had tweeted that “children are being used by some of the worst criminals on earth as a means to enter our country” and added that crime taking place south of the border is “historic, with some countries the most dangerous places in the world.” The president spent his morning tweeting about immigration following the criticism his administration has received for its family separation policy. He also blamed Democrats for holding up immigration reform legislation in Congress as well as for the nation’s immigration and border policies. Homeland Security Secretary Kirstjen Nielsen has defended the child separation policy and said the Department of Homeland Security “will not apologize“ for doing its job.