The frontrunners for the Republican presidential nomination take to the stage in the third GOP debate in Boulder, Colorado - titled "Your Money, Your Vote" - at the University of Colorado, October 28, 2015.

Republican U.S. presidential candidates (L-R) Governor John Kasich, former Governor Mike Huckabee, former Governor Jeb Bush, U.S. Senator Marco Rubio, businessman Donald Trump, Dr. Ben Carson, former HP CEO Carly Fiorina, U.S. Senator Ted Cruz, Governor Chris Christie and U.S. Rep. Rand Paul on stage at the 2016 U.S. Republican presidential candidates debate held by CNBC.

Dr. Ben Carson speaks at the 2016 U.S. Republican presidential candidates debate held by CNBC in Boulder, October 28, 2015.

When it comes to being president of the United States, Carson said his biggest weakness is "not really seeing myself in that position until hundreds of thousands of people tell me to do it."

Businessman Donald Trump (L) speaks as Dr. Ben Carson listens.

Trump leads the Republican field in national polls.

The debate focuses on economic issues, including taxes, retirement spending and jobs.

Ohio Governor John Kasich forcefully makes a point at the 2016 U.S. Republican presidential candidates debate.

Kasich said that tax plans proposed by Carson and Trump "were a fantasy."

Former HP CEO Carly Fiorina speaks as U.S. Senator Ted Cruz listens.

Fiorina said that in order to simplify the tax code, she would restrict its length to just three pages. She repeatedly referred to "crony capitalism" during the debate.

Governor John Kasich, former Governor Mike Huckabee, former Governor Jeb Bush, U.S. Senator Marco Rubio, businessman Donald Trump, Dr. Ben Carson, former HP CEO Carly Fiorina, Senator Ted Cruz, Governor Chris Christie and U.S. Rep. Rand Paul participate in the 2016 U.S. Republican presidential candidates debate held by CNBC.

U.S. Senator Ted Cruz speaks as New Jersey Governor Chris Christie (R) looks on.

Cruz told the audience that he would institute a simple flat tax rate of ten percent, with a business flat tax of 16 percent.

Senator Marco Rubio defended his attendance record and went after mainstream media after the editorial in the Florida Sun-Sentinel calling on him to resign was brought up. He called the editorial "evidence of the bias of the American media today." He said the paper had actually endorsed him in his run for Senate in 2010.

Former Governor Jeb Bush speaks as U.S. Senator Marco Rubio (R) looks on.

"This was a six-year term and you should be showing up to work," said Bush in bringing up the issue of Rubio's voting record on the Hill. Bush added, "The Senate, what is it, like a French work week?"

New Jersey Governor Chris Christie listens as U.S. Rep. Rand Paul (R) speaks.

Senator Marco Rubio fired back at Jeb Bush stating, "I don't remember you ever complaining about John McCain's voting record." He went on to say, "Someone has convinced you that attacking me is going to help you."

Senator Ted Cruz, Governor Chris Christie and U.S. Rep. Rand Paul discuss a point.

Donald Trump (L) and Ben Carson react during the CNBC Republican Presidential Debate.

Governor Chris Christie (C) speaks as Senator Ted Cruz (L) and U.S. Rep. Rand Paul listen.

Donald Trump gestures while he speaks at the 2016 U.S. Republican presidential candidates debate.

Students and protesters gather at the "Free Speech Zone" located at the University of Colorado's Business Field as candidates gather across the street for a forum held by CNBC before the U.S. Republican presidential candidates debate .

People wear the American flag as students and protesters gather at the "Free Speech Zone" located at the University of Colorado's Business Field, while candidates gather across the street for a forum held by CNBC, before the U.S. Republican presidential candidates debate.