While he hits the campaign trail, flashing his million-dollar smile and waving to the adoring crowds, his political hit men are engaged in one of the dirtiest campaigns in recent American history — a campaign where decency is no virtue and moral atrocities are no vice. Not if they help Barack Obama win re-election.

First it was Harry Reid's indecent act on the floor of the U.S. Senate about Mitt Romney not paying taxes in 10 years — an allegation made without so much as a scintilla of evidence to back it up.

It's one thing if a drunk in a bar makes some crazy, unsubstantiated accusation. But this was the leader of the U.S. Senate telling the American people "The word's out he (Mitt Romney) hasn't paid any taxes in 10 years. Let him prove he has paid taxes. Because he hasn't."

Decent people protested Reid's low blow. But the president of the United States wasn't among the decent people. He could have denounced Reid's slimy tactic. But he didn't say a word. And that makes him complicit.

And when the president's friends were asked what they thought, they simply changed the subject to Romney's taxes. The president's press spokesman, Jay Carney, said this was a matter between Harry Reid and Mitt Romney.

Except that no one believes that Harry Reid was freelancing, that he woke up one day and said I think I'll go on the floor of the Senate and say that Romney hasn't paid taxes in 10 years. "The word's out" that the president's re-election team was pulling the strings of their willing puppet.

At the time I thought this was as low as it would get during this campaign. But then came The Ad, produced and paid for by Priorities USA, a super-Pac supporting Barack Obama — and run by a former spokesman for the president.

The ad — casually and incredibly — linked Mitt Romney to the death of a woman who had cancer.