On "Hardball" Wednesday night, Chris Matthews asked me and former San Francisco Mayor Willie Brown to explain the rationale behind the Birther movement as well as mainstream Republicans like Liz Cheney refusing to denounce it. It was tough, but I gave it a shot; here's the video (text continues below):

As I wrote on Tuesday, Liz Cheney refused multiple opportunities to denounce the Birthers on "Larry King Live," and instead blamed President Obama for their abuse: "You know, one of the reasons I think you see people so concerned about this...is people are uncomfortable with having, for the first time ever, I think, a president who seems so reluctant to defend the nation overseas," she said.

King and guest James Carville gave her several more opportunities to separate herself from the Birthers, but she just repeated her talking points about Obama's alleged reluctance to defend America (mighty rich coming from the daughter of "Five Deferments" Dick Cheney). But on Wednesday she told Politico's Ben Smith: "I don't have any question about Barack Obama's right to be President of the United States. My concern is with his policies."

As I said on Hardball Wednesday night, "That's mighty white of you, Liz!"

I give Chris Matthews a lot of credit for venturing to say the Birthers' problem with Obama "isn't documentation, it's pigmentation." When you hear that unhinged woman at Rep. Mike Castle's town hall, wailing "I want my country back!" – well, every time I hear it I get a little more concerned. Obama won the presidency with a bigger share of the popular vote than in any first election since Lyndon Johnson's (and Johnson was of course carried by the tragedy of the Kennedy assassination.) The idea that these people "want their country back" from an allegedly illegitimate president can't be separated from race. It's frankly racist.

Of course the Birther movement persists because it scratches so many itches for the intolerant Republican fringe: It lets them obsess over Obama's father being a Muslim; it lets them remind people he's vaguely "other," with one parent from Kenya, and then, for the trifecta, the obsession with his "birth," subconsciously or not, lets the Birthers focus us on the facts of his conception, that he's the product of – OMG! – interracial sex, that old taboo. There's so much that's unsavory about Obama, from a certain blinkered world view, it's hard to know where to begin – so let's just begin at birth.

Mainstream Republicans have to be asked at every opportunity to denounce the Birther fringe. On Tuesday Matthews went at GOP Rep. John Campbell, a co-sponsor of Birther-inspired legislation that would require future presidential candidates to produce their birth certificates, to get him to disavow the Birther nonsense that Obama isn't a citizen or is otherwise (they actually have a variety of conspiracy theories) not qualified to be president. I've got to hand it to Campbell: he had more integrity than Liz Cheney, and after Matthews' badgering, finally admitted he believed Obama was a citizen and eligible to be president. Cheney refused to do that under the bright lights and big audience of "Larry King Live;" she only did it in the confines of a Politico blog read by Washington insiders.

That way she keeps her credibility with Beltway insiders, while pandering to the incredible shrinking Republican base. She's a pro, that Liz Cheney, a chip off the old Cheney block.