Rubio has long maintained that he would eventually end the White House program that shields some undocumented immigrants who entered before their 16th birthday from deportation, but he has been less clear about when that would happen.

Rubio told CNN’s Jake Tapper on “The Lead” on Thursday that he would revoke the Deferred Action for Childhood Arrivals order immediately, a departure from past comments that suggests it would not take effect until deeper into his presidency.

“I said that DACA has to go away and that it will,” Rubio told Tapper. “I will on my first day in office get rid of it because it’s unconstitutional.”