I think he always looks frightened as if he is afraid to say the wrong thing. Everything he tries to say (emphasis on tries) he fumbles the phrasing and seems insincere. Looks like he’s going through the motions.
It is quite a juxtaposition to Trump who isn’t afraid say anything, and Cruz who is passionate and eloquent.
He seems awfully eager to get our troops into another war
He’s ready to get a redo on the Arab Spring in Libya
And his pro-life position is all about being in the “sweet spot” politically.
Like you say, he fumbles half of his lines.