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DES MOINES, IA - AUGUST 27: Republican presidential nominee Donald Trump speaks at the 2nd annual Joni Ernst Roast and Ride event on August 27, 2016 in Des Moines, Iowa. Trump joined a number of Iowa Republicans who also spoke. (Photo by Stephen Maturen/Getty Images)
DES MOINES, IA - AUGUST 27: Republican presidential nominee Donald Trump speaks at the 2nd annual Joni Ernst Roast and Ride event on August 27, 2016 in Des Moines, Iowa. Trump joined a number of Iowa Republicans who also spoke. (Photo by Stephen Maturen/Getty Images)

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    Could Donald Trump ride GOP senators' coattails?

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Could Donald Trump ride GOP senators' coattails?

The coattail effect usually means a popular presidential contender helps other down ballot candidates in their party, but the opposite could be happening in 2016. CNN's Dana Bash reports.

Could Donald Trump ride GOP senators' coattails?

The coattail effect usually means a popular presidential contender helps other down ballot candidates in their party, but the opposite could be happening in 2016. CNN's Dana Bash reports.