From Comedy Central's Indecision blog:

Riding high after losing his Senate seat by a historically wide margin in 2006, Rick Santorum announced his bid for the White House with confidence.
Naturally, most people assumed this chipmunk stood a better chance of winning the presidency than Rick Santorum did.
Apparently, all he needed to become a legitimate candidate was a sweater without sleeves.
As his popularity grew, Santorum was eventually taken even more seriously than this woman.
Rick Santorum was named the Iowa caucus winner a mere three weeks after votes were cast.

"Hey ladies! Want birth control? Pull my finger!"
Santorum's main financial backer was Foster Friess, who - to his credit - did not charge America a two-drink minimum to hear his bad jokes about women.

Santorum swept the South, winning primaries in Mississippi, Alabama, Tennessee, Oklahoma and Louisiana. This would prove to be the highlight of his year and the lowlight of Mississippi, Alabama, Tennessee, Oklahoma and Louisiana's year.

Despite his insurgent victories, by April the math was clear: Rick Santorum was bowling alone, in a special lane for people who would not be their party's nominee.
On April 10, 2012 we bid farewell to Rick Santorum's presidential campaign. So long, Rick, and thanks for all the easy jokes. See you in 2016!
Re: Farewell, Rick Santorum: A Photo Retrospective
I'd have voted for the chipmunk. Look at those widdle cheeks!
Nice photo retrospective.