Have you ever heard him say nuclear weapons? Me, neither. It's nucular. LOL
Seriously, I haven't heard him say sales tax, flat tax or anything else. That doesn't mean he is against it. Does he have anything to lose by going with the NRST? No. No reelection, no VP to get elected. Already got house and senate.
Before they do a national sales tax or flat tax to replace the income tax, they need to do a constitutional amendment repealing the 16th.