http://www.mediaite.com/tv/bernie-sanders-to-liberty-u-america-was-founded-on-racist-principles/In a very narrow sense, yes of course, just like every other country in the world at the time, the US prevented all peoples from expressing themselves democratically and while the institution of slavery was protested, it was not outlawed.
That being said, it is incredibly naive and narrow-minded to hold the founding fathers to a higher standard that places them outside of the 18th century. The US constitution and its founding documents established and enshrined liberal principles that gave its citizens unparalleled rights at the time. Of course it was not perfect, but the wording of constitution was the basis upon which slavery was eventually outlawed and equality under the law restored to the nation.
I would have expected more from Sanders to be honest.
