Ted Cruz, Donald Trump, Jeb Bush, Scott Walker, and maybe Rubio have all already done clowny things. I'm voting more.
Of all of these guys, only Trump is a clown. Even Ted Cruz, who represents the extreme Tea Party sect of Republicans, is not all that out there, in comparison to Michelle Bachmann and Herman Cain, and none of these guys are retreads like Rick Santorum (who lost big in his last campaign) and Newt Gingrich (who was run out of his Speakership on a rail).
What looks like the Clown Car is the Congressional Republicans, and especially the House Republicans. The middle-of-the-road voters who are legitimately undecided are few, but they are critical and they don't look kindly on Government Shutdowns. The Nutty Base of the GOP doesn't get that. It's why they lost the 2012 election; a race they should have won.