Mitt Romney emerges as standout Trump critic

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Amid GOP backlash against President Trump for his decisions on Syria and the G-7, Senator Mitt Romney has emerged as a standout critic. Romney was asked in an interview with the Atlantic this weekend about impeachable acts, and responded "I'll know it when I see it." Mike Murphy, a former senior advisor to the Utah Senator, and an MSNBC political analyst, joins Andrea Mitchell to provide his insight.