Senate majority leader Harry Reid took to the leftwing Huffington Post to launch what may be the most negative attack of the presidential campaign to date. The Nevada senator insinuated that he knows a guy who knows a guy who swears up and down that Mitt Romney paid no taxes for 10 years. Reid is trying to fill the information vacuum left by Romney’s decision not to release more of his past tax returns — by filling that vacuum with a smear.

Saying he had “no problem with somebody being really, really wealthy,” Reid sat up in his chair a bit before stirring the pot further. A month or so ago, he said, a person who had invested with Bain Capital called his office.

“Harry, he didn’t pay any taxes for 10 years,” Reid recounted the person as saying.

“He didn’t pay taxes for 10 years! Now, do I know that that’s true? Well, I’m not certain,” said Reid. “But obviously he can’t release those tax returns. How would it look?”

Reid is taking his cues on handling facts from ABC’s Brian Ross, it seems. Reid added that Romney’s late father George would be “embarrassed” by his son.

“His poor father must be so embarrassed about his son,” Reid said, in reference to George Romney’s standard-setting decision to turn over 12 years of tax returns when he ran for president in the late 1960s.

George Romney passed away in 1995.

Under Reid’s tenure, the Senate has gone more than three years without passing a national budget.