Better than that - he is in the top 3 right behind Mike Lee and Ted Cruz. Here is my list based on the Heritage Foundation rankings.

Other than Cruz and Lee, who have tried to stop Obama's agenda?
If Republicans aren't stopping Obama and the progressive agenda in general, then they're dead to me.
Why don’t you post those cloture votes Roberts made, as well.
You know, those votes that allowed a bill a floor vote, so he could vote
against it, after he voted for it with his cloture vote.
I don’t know of many other conservative incumbents in 2014. Inhofe, Scott and Risch maybe. The others are all weak.