Marco Rubio, center, and Jeb Bush, left, argue a point as Donald Trump, looks on during the CNBC Republican presidential debate at the University of Colorado, Wednesday, Oct. 28, 2015, in Boulder, Colo.
Marco Rubio, center, and Jeb Bush, left, argue a point as Donald Trump, looks on during the CNBC Republican presidential debate at the University of Colorado, Wednesday, Oct. 28, 2015, in Boulder, Colo. Mark J. Terrill AP
Marco Rubio, center, and Jeb Bush, left, argue a point as Donald Trump, looks on during the CNBC Republican presidential debate at the University of Colorado, Wednesday, Oct. 28, 2015, in Boulder, Colo. Mark J. Terrill AP