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Donald Trump is beginning a new line of attack against Hillary Clinton: her husband Bill Clinton's infidelities.

Former Green Beret Ben Collins said on "Outnumbered" today that the Republican nominee should avoid personal attacks and stick to substantive issues.

"Donald Trump has a choice right now, and he can either win the argument or he can win the presidency," Collins said.

He explained that countless polls show the single biggest question many Americans have about Trump is if he has the temperament to be commander-in-chief.

"He shouldn't be talking about this, dredging this stuff up and going on the attack," Collins said. "In my opinion, he should be talking to those undecideds - if there are any - those suburban moms that the Clintons first identified."

"He needs to be targeting a very specific audience, and I think this just kind of clouds his message."

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