House Speaker John Boehner (R-Ohio) said in an interview aired late Wednesday that it’s “inconceivable” someone didn’t inform President Obama about the IRS’s targeting of conservative groups. “It’s pretty inconceivable to me that the president wouldn’t know,” Boehner said in an interview with Fox News Channel’s Greta van Susteren.

“I’m just putting myself in his shoes. I deal with my senior staff every day. And if the White House had known about this, which now it appears they’ve known about it for about a year, it’s hard to imagine it wouldn’t have come up in some conversation.”

House Speaker John Boehner can't imagine President Obama didn't know about the IRS investigation until it became public:And why can't he conceive of this?Note that Boehner says the White House has known about the IRS probe for about a year, but according to the White House, they first learned about it in late April. No evidence has emerged suggesting that's untrue, which means that Boehner's explanation for why he can't imagine Obama didn't know is based on imaginary fact.

Adding to the irony, it turns out that House Republicans have known about the probe for roughly a year—the IRS Inspector General informed Darrell Issa and Jim Jordan of the inquiry last July. So, by Boehner's own logic, it's "inconceivable" that Boehner didn't know about the IRS inquiry, yet he remained silent. The logical conclusion from that flows from that "fact"—which was established by the first constructive law of inconceivability—is that House Speaker John Boehner covered up the IRS investigation.

Sure, those logical leaps are nonsense, but it's no different than what Republicans are doing here. Every day they have a new theory, but the end result of their theory is always the same: Obama is Nixon. Sure, as Steve Benen writes, when the IRS story first broke, Republicans accused President Obama of using the IRS as a political hit squad against his enemies. But that theory has been debunked, so now they are trying to accuse him of covering up knowledge of the investigation into the activities after the activities had been stopped.

Of course, this theory won't work, because even if the White House is lying (a claim for which there is no evidence), we know that Republicans were aware of the probe. Nothing was stopping them from talking about it publicly, but they didn't. But even though it's clear this latest Republican theory is going to go up in smoke, it doesn't mean they're going to stop arguing that Obama = Scandal = Nixon. It just means they've yet to imagine their next theory on why.