Washington — Marco Rubio, the former state House speaker challenging Gov. Charlie Crist in Florida’s GOP Senate primary, gave a well-received speech this morning at CPAC, the Conservative Political Action Conference. Introduced by one of his best-known boosters, Sen. Jim DeMint (R., S.C.), Rubio explained to activists the purpose of his primary challenge. “The U.S. Senate already has one Arlen Specter too many,” Rubio said, to cheers. He also called his campaign part of “the greatest pushback in American history.”

Rubio began his speech by focusing on his roots, speaking about his childhood and the inspiration of his Cuban grandfather. He also stirred some laughs with jokes about the recent D.C. blizzard, calling it the “best thing that happened to the American economy in twelve months.” He also chided President Obama for using teleprompters, saying that the snow prevented Congress from voting on bills (more cheers) and the president from finding a teleprompter (more chuckles).

But Rubio’s humor wasn’t the real highlight. It was his tough rhetoric on national security that electrified the attendees. Speaking about “radical Islamic” terrorists like the Christmas Day bomber, Rubio said that the U.S. must “bring them to justice in a military tribunal, not a civilian courtroom in Manhattan.” He added: “We will punish their allies like Iran. We will stand with our allies like Israel. We will target and we will destroy terrorist cells and the leaders of those cells. The ones that survive, we will capture them. We will get useful information from them.”

In an interview with National Review Online following his address, Rubio acknowledged that the national-security parts of his speech received the largest applause — a standing ovation, no less. “Apart from our domestic challenges, this audience — and the rest of America — recognize and understand that the world is a very dangerous place — that there are people out there intent on imposing their world view. Our enemies feel like the only thing standing in their way is the United States. That’s why they attack us. We need to recognize that as a threat and respond to it like a threat, not like terrorism is some diplomatic disagreement we can easily solve. In every respect, this fight is a war, unfortunately.”

This was Rubio’s first time at CPAC, but says he has watched it for many years on television. “This was probably the biggest crowd I’ve probably ever spoken to,” he says. “It was friendly crowd, for sure.”