Why didn't Romney pick Santorum?

[Vosem]

Beyond what Xahar correctly said, Santorum's success was also a fluke resulting from other (and in some cases more obvious/qualified/electable) anti-Romneys having already risen up, peaked, and fizzled out for a variety of reasons owing to gaffes. The examples I remember best are Rick Perry and Herman Cain. It would be like choosing Ben Carson as VP in 2016 if only his momentum had held on until Iowa.

The whole logic of the Santorum campaign never really made sense because as has already been mentioned, his most recent election result was losing re-election by 17 points in a Swing State. Imagine if someone was fired from middle management at a major corporation and then applied to be its CEO. Santorum's campaign was taken about as seriously as that would be.

Eh...Santorum's presidential campaign was an incredible example of being at the right place at the right time, but he won the Iowa caucus and came within single-digits in pivotal Midwestern states. He was taken quite seriously by the primary electorate.

As to why he wasn't considered as a vice-presidential choice, yeah, all the stuff in this thread applies.