Former Florida Governor Jeb Bush is calling on President Donald Trump to end the “heartless” policy of separating immigrant children from their parents at the U.S. border.

“Children shouldn’t be used as a negotiating tool,” Bush tweeted on Monday. “@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.”

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. https://t.co/OOjv0vNeVg — Jeb Bush (@JebBush) June 18, 2018

The failed presidential candidate’s plea came in response to President Trump’s tweet in which he vowed to stop “some of the worst criminals on earth,” from using children to illegally enter the U.S.

“Children are being used by some of the worst criminals on earth as a means to enter our country,” President Trump said. “Has anyone been looking at the Crime taking place south of the border. It is historic, with some countries the most dangerous places in the world. Not going to happen in the U.S.”

Bush joins a chorus of Republicans, such as Nebraska Senator Ben Sasse and Ohio Governor John Kasich, calling for the policy to be halted.

“Let’s get it right. We’re America,” the Ohio governor said in a video posted to Twitter last Friday. “We have a big heart. We love people. At the end of the day, we don’t want to create an image that we don’t care, because we really do.”

The Justice Department announced April 6 the implementation of a new “zero-tolerance” policy, an effort by the Trump administration to reduce illegal border crossings into the U.S.

Illegal aliens smuggling minors across the border posing as families has sharply increased more than 300 percent in the past year.

Department of Homeland Security officials say 1,995 immigrant children were separated from adults between April 19 and May 31. The children are provided with food, shelter and medical care administered by the Department of Health and Human Services.