Senate Majority Leader Harry Reid says he heard from a Bain investor who heard that Mitt Romney paid exactly zero taxes for 10 years, Reid tells The Huffington Post's Sam Stein and Ryan Grim. Romney says he'll only release two years of tax returns, and says he doesn't remember if he's ever paid less than he did in 2010, 13.9 percent. His campaign denies the insinuations of President Obama's campaign that Romney paid no taxes at some point. Some have theorized that Romney might have paid no taxes in 2009, though there's a solid bit of counter-evidence to that claim. But Reid's accusation goes way beyond that.

The Huffington Post calls its interview with Reid "wide-ranging." That's one word for it. Reid said Romney's dead father would be "so embarrassed" by his son. Then he recounted how a Bain Capital investor called him a month ago and said, "Harry, he didn't pay any taxes for 10 years." Acknowledging that's awfully slim evidence, Reid offers this massive asterisk:

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

Boy, that sounds familiar, as The Atlantic's Max Fisher pointed out. There are a lot of explosive things politicians haven't been certain about in recent years. One stands out more than the others. For example, Colorado Rep. Mike Coffman:

"I don't know whether Barack Obama was born in the United States of America. I don't know that. But I do know this, that in his heart, he’s not an American. He’s just not an American."

Coffman later apologized, saying he misspoke. Donald Trump tried this last March, before going full birther. Last fall, Rick Perry kept it slightly more subtle in his interview with Parade:

Governor, do you believe that President Barack Obama was born in the United States?

I have no reason to think otherwise. 

That’s not a definitive, “Yes, I believe he”—

Well, I don’t have a definitive answer, because he’s never seen my birth certificate. 

But you’ve seen his.

I don’t know. Have I? 

Reid has stolen this "What? All he has to do is release the document" trick from is idelological enemies.