Sen. Marco Rubio (R-FL) said in a Thursday interview that Donald Trump will have to “answer some questions” about a Newsweek report alleging one of his companies broke the Cuban trade embargo in 1998.

“This is something they’re going to have to give a response to. I mean, it was a violation of American law, if that’s how it happened,” he said on the ESPN/ABC Capital Games podcast. “I hope the Trump campaign is going to come forward and answer some questions about this, because if what the article says is true — and I’m not saying that it is, we don’t know with a hundred percent certainty — I’d be deeply concerned about it. I would.”

Rubio endorsed Trump in May, three weeks before announcing he would seek re-election to the U.S. Senate. When Rubio and Trump competed in the Republican presidential primary in the Sunshine State, Trump won the popular vote in every county except Miami-Dade, the most populous in the state and home to a large Cuban-American population.

After President Barack Obama called for an end to the Cuban embargo in March, Rubio, then still a candidate for the Republican nomination for president, said he would “absolutely” roll back Obama’s actions towards normalizing relations with Cuba if elected.

“We could have used, and can use, economic sanctions through the embargo as a leverage to gain democratic concessions and openings for the Cuban people in exchange for alleviating some of these conditions,” Rubio said at the time, saying he thought the Obama administration was “in violation of the law” for acting without Congressional approval.