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MANCHESTER, NH - FEBRUARY 06:  Republican presidential candidates Jeb Bush and Sen. Marco Rubio (R-FL) participate in the Republican presidential debate at St. Anselm College February 6, 2016 in Manchester, New Hampshire. Sponsored by ABC News, the Independent Journal Review and Google, this is the final televised debate before voters go to the polls for the New Hampshire primary on February 9.  (Photo by Joe Raedle/Getty Images)
MANCHESTER, NH - FEBRUARY 06:  Republican presidential candidates Jeb Bush and Sen. Marco Rubio (R-FL) participate in the Republican presidential debate at St. Anselm College February 6, 2016 in Manchester, New Hampshire. Sponsored by ABC News, the Independent Journal Review and Google, this is the final televised debate before voters go to the polls for the New Hampshire primary on February 9.  (Photo by Joe Raedle/Getty Images)

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Rubio on running against one-time mentor Jeb Bush

In an exclusive interview with Jake Tapper, Sen. Marco Rubio revealed why he made the difficult decision to run against his one-time mentor Gov. Jeb Bush.

Rubio on running against one-time mentor Jeb Bush

In an exclusive interview with Jake Tapper, Sen. Marco Rubio revealed why he made the difficult decision to run against his one-time mentor Gov. Jeb Bush.