Washington (CNN) - Unlike fellow Republican Senate hopeful Marco Rubio, former Rep. J.D. Hayworth did not get top billing at the Conservative Political Action Conference. Far from it.
But Hayworth, who is mounting a GOP primary challenge to Sen. John McCain in Arizona, did appear down the hall from the main ballroom on a small panel discussion about free speech - and spent his allotted five minutes thrashing his opponent.
"You wonder why John McCain is facing this challenge?," Hayworth told the small audience of conservative activists in the room. "It's because after 28 years in Washington, he may claim conservatism, but sadly those underpinnings have deserted him."
Given the title of the panel - "They Want Us To Shut Up: Saving Freedom and the First Amendment" - Hayworth drilled down on McCain's long crusade to reform campaign finance laws, a fight many conservatives believe is an assault on free speech.
But Hayworth said McCain has undergone a "campaign year conversion to conservatism," because he remained relatively silent after the Supreme Court overturned decades of campaign finance regulations earlier this year.
Hayworth then likened McCain to the left-leaning media watchdog Media Matters and liberal billionaire George Soros before taking his seat on the panel dais.
Arizona Republican Party Chairman Randy Pullen was present in the room for Hayworth's remarks.
Pullen, who is officially neutral in his role as chairman, called the primary "a real competitive race." He said Hayworth "has a lot of support," but added he "has a lot of ground to make up" against McCain, who has been campaigning for re-election since he fell short in the 2008 presidential race.
"But J.D. is a hard campaigner, so I expect this to be a very, very tough campaign," Pullen said.