As it's becoming increasingly clear that the upcoming midterms will be a referendum on President Obama - and very possibly a major victory for Republicans - some Democrats are resorting to desperate, ad hominem attacks, such as Rep. Charlie Rangel's (D-NY) recent controversial comments, charging (among other things) that some Republicans "believe that slavery isn’t over."

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Desperation comes into play when you don't have any arguments, Charles Krauthammer said on "Hannity" last night.

And not only are Obama's poor track record and low approval numbers next to impossible to defend, but now it's clear that his administration is simply ineffective, as well.

"There’s an overlay of sheer incompetence. In the second year of the administration, all of this stuff was aspirational. It was in the future," Krauthammer said.

"Well, now we’ve seen six years of Obama-ism, and actually the problem is not just the ideas and the ambitions, it’s the fact that they are just incompetent."

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As for ad hominem attacks such as Rep. Rangel's, don’t even dignify accusations of racism with a response, Krauthammer said, because then you’re conceding the premise.

"I oppose the president because of his policies. I have since the beginning of his administration," Krauthammer said. "If someone wants to imply it's on account of his race, I will not give him the dignity of a response. That’s not America."

Watch more above and be sure to pick up Krauthammer's best-selling book, "Things That Matter."

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