"Speaking ill" of his fellow Republicans, presidential candidate Rand Paul flagrantly violated Ronald Reagan's "Eleventh Commandment" on Sunday when he slammed some of his GOP colleagues over their hawkish foreign policy, Politico reported.

"There's a group of folks in our party who would have troops in six countries right now -- maybe more," the Kentucky senator told hundreds of activists at an event in New Hampshire, where the first-in-the nation primaries are traditionally held.

His approach to foreign policy would be a distinguishing factor in the increasingly crowded field of GOP candidates vying for their party's 2016 nomination, he noted.

"This is something, if you watch closely, that will separate me from many other Republicans," Paul insisted. "The other Republicans will criticize Hillary Clinton and the president for their foreign policy, but they would have done the same thing -- just 10 times over!"

With respect to the 2012 attack on the U.S. consulate in Benghazi, often seen as a liability for Clinton, the senator wondered: "Why the hell did we ever go into Libya in the first place?"

Arizona Sen. John McCain did not waste time -- nor mince words -- when he retorted on Fox News's "Fox and Friends" on Monday morning, the Hill noted.

Paul "just doesn't understand" foreign policy, the GOP's 2008 presidential nominee accused.

"He has displayed this kind of naïveté since he came to the Senate," McCain charged.

South Carolina Sen. Lindsey Graham, widely viewed as a foreign-policy hawk, voiced a similar point of view on MSNBC's "Morning Joe," Talking Points Memo said.

"Generally speaking, he's been more wrong than right," he said about Paul. "He has an isolationist view of the world that I don't share. And I like him, but he's his father's son," Graham added.

The U.S. Air Force veteran was referring to longtime Texas congressman Ron Paul, who as a presidential candidate proposed a decidedly libertarian foreign policy. His son, however, framed his views as "more realpolitik than isolationist" in New Hampshire, Politico detailed.

"Every time we've toppled a secular dictator, a secular strongman, we've gotten chaos and the rise of radical Islam," he said. "We have to decide when getting involved is good and when it's not so good," Paul insisted.