Cruz has long said that his flat tax plan allows us to get to the Fair Tax.
Yes but his current tax plan has no details how that can be attained.
Neither does Trump’s.
Both plans will stimulate the economy, but both have a short shelf-life.
In sum, neither tax plan of Cruz or Trump is distinct enough to change their support levels between the two candidates. But they are distinctive enough to separate them from any plan or position of a democrat. Huckabee is a longtime FairTax supporter and perhaps some of the other candidates. Trump and Cruz are distinguished from the others based on factors other than taxes.