Donald Trump and Ben Carson say they will boycott if CNBC extends the length of the debate.\rbr\rbrRepublican presidential candidates Donald Trump and Ben Carson have threatened to boycott the next primary debate if CNBC does not adhere to their .\rbr\rbrGOP Presidential Candidates Threaten to Boycott Next Debate The race for president, lots of action on the campaign trail as Donald Trump and Ben Carson .\rbr\rbrDonald Trump and Ben Carson say they will boycott if CNBC extends the length of the debate. Republican presidential candidates Donald Trump and Ben .