[Antoninus]

Does this count as an ad hominem?

This guy is not a constructive critic. He's a crypto-lib who managed to get himself the chair of the ACU.

[Arguendo]

Yes, it's an ad hominem, though it's at least a fair attack on his conservative credentials. If he endorses a candidate his conservative credibility matters. But if he makes a fairly objective comment on her 2012 credentials, such as what I'm copying below, that's something that can be addressed on its face.

“What she’s proved is that she’s a very popular person, she’s an incredible political property, in the early stages as governor she made a real impression, she was a reformer, she was all of those things. But now she hasn’t followed through. Her pipeline project is up in the air, and it’s as if she dropped it to run after something else. But she hasn’t even made clear what it is she’s running after."