In an appearance at the Reagan Library Saturday night, Sen. Rand Paul (R-Ky.) took a dig at John McCain over the Arizona senator's recent visit to Syria.

"I'm very worried about getting involved in a new war in Syria," Paul said, because while President Bashar al-Assad is "a bad guy," there's al-Qaeda and al-Nusra (an al-Qaeda linked Islamist group) on the other side.

"They say 'there are some pro-Western people, and we're going to vet them,' well apparently we had a senator over there who had his picture taken with some kidnappers, so I don't know how good a job we're doing vetting those who are going to get the arms," he said, to applause.

McCain traveled to Syria on Memorial Day weekend and met with rebels, who he has argued should receive arms from the United States. A Beirut newspaper reported that two of the men he was photographed with during the trip were involved in kidnapping Lebanese Shiite pilgrims a year ago. But that report has been dismissed by people involved in the meeting, and it originally came from a pro-Hezbollah television station.

The jab comes about 38 minutes into this video:

The comment came during a question-and-answer session after Paul's speech. In his remarks, Paul called for the Republican Party to be more inclusive, saying the party needs to focus on defending the Bill of Rights. Among other things, he said the GOP should embrace "people with tattoos and without tattoos" and show that the party cares about the environment, telling the audience, "I compost."

Earlier this year McCain harshly criticized Paul for launching a filibuster against the potential use of drone strikes against civilians in the United States, calling the senator and his allies "wacko birds."