President Donald Trump passionately reiterated his commitment to ending birthright citizenship for children born in the U.S. to parents who aren’t citizens during a Florida rally on Wednesday night.

His comments come days after he told “Axios on HBO” that he could revoke the policy, a right enshrined in the 14th Amendment, via executive order.

“Hundreds of thousands of illegal immigrant children are made automatic citizens every year because of this crazy policy, and they are all made instantly eligible for every privilege and benefit of American citizens at a cost of billions of dollars a year,” Trump claimed. “That’s what it costs ― billions.”

Trump’s estimate likely comes from a study put out by an anti-immigration think tank, the Center for Immigration Studies, earlier this month. The Pew Research Center found in 2016 that such births were on the decline and that in 2014, babies born to undocumented immigrants on U.S. soil accounted for 7 percent of births that year.

“The Constitution does not — I say that to the media — does not require it. Read it. Because illegal aliens are not subject to the jurisdiction of the United States,” Trump insisted, though legal scholars and even House Speaker Paul Ryan (R-Wis.) say Trump’s got that wrong.

Trump doubled down on his commitment to upending the 14th Amendment to the riled-up crowd chanting, “USA! USA!”

“We will keep the criminals, the drug dealers, we will keep them all out of our country,” he said. “We will get rid of all of this. We will end finally birthright citizenship.”