Language Log » Severely X

Liberman writes:

In the Corpus of Contemporary American English, 'severely' precedes a modifier 959 times, and in 939 of these, the following word is something generally regarded as regrettable if not downright bad. In descending order of frequency: disabled, depressed, ill, limited, injured, retarded, impaired ....

So, since Mitt says he's "severely conservative," he either doesn't know what he's saying, or he's not sincere about it.