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What has changed heading into the second GOP debate

This week’s big political event is the second Republican debate on Wednesday. And it’s worth recapping what has changed in the month since the first one.

Republican presidential candidates take the stage for the first Republican presidential debate at the Quicken Loans Arena, Aug. 6, 2015, in Cleveland. (Photo by John Minchillo/AP)
Republican presidential candidates take the stage for the first Republican presidential debate at the Quicken Loans Arena, Aug. 6, 2015, in Cleveland. AP

Chuck Todd

Chuck Todd is NBC News' chief political analyst and the former moderator of "Meet The Press."

Mark Murray