No, not ONLY lefties, but they flock there in spades. They'd make the perfect venue for executing their foes - us.
Having performed at the largest Renfest in the country for several years, I can tell you that your statement is not at all true of the patrons.
The patrons frankly aren't there to be political . . . they're there to be entertained. And you'd be surprised how many armed services members we get.
Now, as regards the performers, I'm in quite a minority. There's only one person at TRF as far to the right as I am . . . and here he is. I give you Sholo the Nubian! (Don't let the look fool you . . . he's really a big teddy bear.)