Kentucky Sen. Rand Paul seized on Friday’s terrorist attacks in Paris to criticize GOP presidential rival Sen. Marco Rubio Saturday.

Speaking at a Republican presidential forum in Orlando, Paul said Rubio’s opposition to one of his amendments to the 2013 Gang of Eight immigration bill, which would have enhanced screening requirements for those entering the country, damaged national security.

“Two, three years ago, I introduced a bill, or an amendment, to the immigration bill that would have provided for more scrutiny of people coming into our country: refugees, immigrants, students,” Paul said, when asked about his response to Friday’s attacks. “They would have had background checks and they would have had a much higher degree of scrutiny. And the point I made in my speech was, I introduced this to Rubio and (Democratic Sen. Chuck) Schumer’s immigration bill and then Rubio and Schumer and all of the authors voted against any conservative amendments. And I think that was a mistake, not only for the bill, but also for our national security.”

“Marco and Schumer basically had a secret deal to block all amendments,” Rand alleged.

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Asked specifically about what he would do on the ground in Syria and Iraq against the Islamic State of Iraq and Greater Syria in light of the attack, Paul demurred and responded by again criticizing Rubio and focusing on immigration policy.

“I think the main thing we need to know is who’s in our country and are they going to harm us,” he said, again referring to his blocked amendment, which he said would have instituted heightened scrutiny for those seeking to enter the U.S. from 25 countries with radical Islamist elements.

As Rubio has surged in recent weeks, he’s become a larger target for his rivals, with Sen. Ted Cruz suggesting Friday that Rubio’s support for the immigration bill meant he supported Iranian leader Ayatollah Khomeini obtaining a nuclear weapon.

Paul added that he was opposed to the U.S. accepting any refugees from ISIS-controlled territory. “I don’t think we need to be admitting large amounts of Syrian refugees into our country,” he said, suggesting that Saudi Arabia should make room for them.

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