There was a poll out yesterday, showing many potential GOP presidential candidate's current favorability ratings in Iowa. Portman was the only one underwater aside from Christie, though to be fair no one knows him (because he's dull).
Paul Ryan: 75/14 (+61)
Rick Perry: 64/23 (+41)
Scott Walker: 49/10 (+39)
Marco Rubio: 54/16 (+38)
Rand Paul: 59/24 (+35)
Mitt Romney: 65/30 (+35)
Ted Cruz: 52/18 (+34)
Ben Carson: 41/8 (+33)
Mike Huckabee: 59/30 (+29)
Bobby Jindal: 41/14 (+27)
Jeb Bush: 50/28 (+22)
Rick Santorum: 52/30 (+22)
John Kasich: 17/7 (+10)
Mike Pence: 10/10 (0)
Rob Portman: 9/10 (-1)
Chris Christie: 35/45 (-10)