Just hours after Sens. John McCain (R-Ariz.) and Lindsey Graham (R-S.C.) slammed Sen. Rand Paul on the Senate floor, conservatives are turning on the Republican Party's "old bulls."

In a floor speech this morning, McCain accused Paul of using the filibuster to "fire up impressionable libertarian kids." Graham claimed Paul was ignoring national security threats, using a ludicrous chart to illustrate his point,

"It was embarrassing," a senior Republican Senate aide told Business Insider. "It definitely looked like two guys whose time has passed. They are behind history, and they are the only people in the room who don't know it yet."

By Thursday afternoon, conservative grassroots group FreedomWorks was already asking supporters to sign a petition demanding McCain apologize to Paul.

"Senator Rand Paul's filibuster on the Senate floor was not a political stunt to 'fire up impressionable libertarian kids,'" the petition reads. "I am a full grown adult and I agree with Sen. Paul that the President of the United States does not have the authority to assassinate American citizens on American soil without due process."

The Young Americans for Liberty, a conservative libertarian organization, created a hashtag, "#DieWithMcCain," that played off the "#StandWithRand" moniker that took over Twitter on Wednesday.

"These 'libertarian kids' are the future. It's just a matter of whether or not the GOP will stand with Rand and remain relevant; or turn their backs on the next generation and die with McCain," executive director Jeff Frazee said.

Erick Erickson, the editor-in-chief of the conservative blog RedState, linked to a story of the duo's criticism and suggested that Graham could face a primary challenge in South Carolina's Senate race in 2014.

Wonder if stuff like this will incentivize a credible candidate to take on Lindsey Graham. washingtontimes.com/blog/inside-po… — Erick Erickson (@EWErickson) March 7, 2013

Meanwhile, the Drudge Report mocked McCain and Graham as "old bulls":