U.S. Sen. John McCain doesn’t face voters again until 2016 … but he’s already being challenged to a U.S. Senate debate by a more conservative opponent.

So … is somebody getting a super-early head start on their GOP primary campaign?

No … McCain has been challenged to a debate in early-voting South Carolina, where his longtime ally U.S. Sen. Lindsey Graham is ducking a debate challenge issued by his independent conservative rival, Thomas Ravenel.

After Graham refused to respond to Ravenel’s challenge for a series of town hall debates in which individual South Carolinians posed questions to candidates, Ravenel decided to take his challenge straight to McCain.

“The puppet is too afraid to debate me so I might as well start challenging his puppet masters – beginning with John McCain,” Ravenel said.  “The people of South Carolina deserve a series of real debates in which their concerns are heard and their questions are asked and answered by the candidates.  If Lindsey Graham is too afraid to defend his views in such a forum – then I’m going to start challenging the powerful interests that are pulling his strings in Washington D.C.”

McCain and Graham are among the U.S. Senate’s most strident defenders of the American military-industrial complex – a costly special interest Ravenel has targeted in the past.  Graham in particular has taken his advocacy on behalf of this establishment icon to borderline ridiculous extremes.

In addition to targeting Graham’s “puppet masters,” Ravenel has wrapped his challenge in an “us versus them” cloak – seeking to position Graham as out of touch and unsympathetic to the plight of his constituents.

“Lindsey Graham has time to meet with Barack Obama nineteen times, to appear on all the Sunday morning talk shows and to fearmonger through the media – but apparently he doesn’t have the time to hear the concerns and face the criticisms of hard-working South Carolinians,” Ravenel said.  “That’s his prerogative, but by refusing to participate in these debates Lindsey Graham is telling South Carolinians that they aren’t worth his time.   He’s also telling them what many of them already know – that his abysmal record of wasting our tax dollars, attacking our liberties and unnecessarily harming our friends and loved ones in the military is indefensible.“

“If he won’t defend that record, maybe John McCain will,” Ravenel added.

That sound you hear?  It’s a gauntlet being dropped …

Will Graham or McCain pick it up?

Ravenel also said that the longer Graham refuses to debate, “the more I will expose him as being beholden to Washington’s special interests.”

“If Lindsey Graham thinks he can run out the clock on this election, he’s got another thing coming,” Ravenel said.  “I’m not just going to shame him, I’m going to shame the interests subsidizing his ongoing betrayal of our state and its people.”

We’ll be sure to let you know if McCain takes Ravenel up on the invite …