A potential GOP primary challenger to President Donald Trump explained further why he was stepping in and why he was concerned about Trump's leadership.

A potential GOP primary challenger to President Donald Trump explained further why he was stepping in and why he was concerned about Trump's leadership.

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Potential GOP challenger: Trump 'showed contempt for the American people'

A potential GOP primary challenger to President Donald Trump explained further on Monday why he was stepping in and why he was concerned about Trump's leadership.