The concern is that the conservative that hopefully wins Oval Office in 16 will be open to letting patriots get her/him up to speed on the federal governments constitutionally limited powers.
I don't live on hope.
Since Carson doesn't understand that our rights come from God, re: the 2nd Amendment, he's not ready for Prime-Time.
Cruz, on the other hand, had the Constitution memorized by the time he was 13, and has argued successfully, 9 conservative cases in front of the Supreme Court.
Additionally, he continually and consistently, makes sound conservative constitutional policy positions based on whether or not his position passes constitution muster.
CRUZ or LOSE!