The sudden sexual piety of Democrats who say Anthony Weiner must resign.

After all the self-serving, morally selective posturing we've heard from Rep. Anthony Weiner over the past two weeks, it's such a relief to see him finally being thrown overboard by his self-serving, morally selective colleagues.

On Tuesday, former Virginia Gov. Tim Kaine, having just stepped down as chairman of the Democratic National Committee, called for Weiner's resignation while campaigning for the U.S. Senate. The next day, another ex-DNC chairman, former Pennsylvania Gov. Ed Rendell, delivered the same message. So did Pennsylvania Rep. Allyson Schwartz, who chairs the candidate recruitment office of the Democratic Congressional Campaign Committee.

According to these brave Democrats, Weiner must go because he has violated important moral principles, which, for some reason, Democrats ignored when the same principles were less politically convenient.

Rendell, appearing Wednesday on Hardball, argued that a picture of Weiner's namesake, apparently sent by the congressman to a woman over the Internet, "puts it over the limit. I think he's got no choice now but to resign." Weiner "obviously has some form of emotional or mental illness," Rendell concluded. "He should resign. He should get treatment."

That's odd, because I could have sworn that a dozen years ago, when President Clinton was caught ejaculating on a White House intern—and lying about it under oath  in a sexual harassment suit that he settled with another woman for $850,000—Rendell was his staunchest defender. Far from expressing outrage at Clinton's behavior, Rendell, who was then the mayor of Philadelphia, said it was "not the American people's business," and he blamed Independent Counsel Ken Starr for putting "548 descriptions of sex" in his report. Rendell excused Clinton's perjury, suggesting that other presidents had cheated on their wives and lied under oath. "Almost everyone in the country would understand someone lying to protect their wife and daughter," Rendell argued. He said Monica Lewinsky's age was no big deal, since President Eisenhower had also had a "power relationship" over his mistress. When reporters asked whether perjury undermined the criminal justice system, Rendell shrugged, "I was an assistant D.A. and [in] every case I prosecuted, somebody lied once."

Rendell didn't just defend Clinton. He chastised other Democrats who shunned the president. Two months after Clinton admitted to an inappropriate relationship with Lewinsky, Rendell hosted him at a fund-raiser. When Joe Hoeffel, a Pennsylvania congressional candidate, skipped the event, Rendell told the press that "in light of the charges, I won't be a fair-weather friend. And frankly, I was disappointed in those Democrats who were."

Rendell became governor of Pennsylvania, Hoeffel became a congressman, and six years later, Hoeffel was succeeded by Schwartz. In the interim, Schwartz, who was then a Pennsylvania state senator, ran for the U.S. Senate seat held by Rick Santorum. Schwartz blasted the Senate's impeachment trial of Clinton, calling it "politically motivated." She urged Congress to "move on" and shifts its attention to "the real concerns facing American families."

How times have changed. Schwartz, now a top official at the DCCC, has gained a deeper understanding of sexual morals. "We have the right to expect better behavior from members of Congress, leaders of our country," she declared Wednesday. "In light of Anthony Weiner's offensive behavior online, he should resign."

Kaine, too, finds Weiner's conduct intolerable. "Lying is unforgivable, lying publicly about something like this is unforgivable, and he should resign," the senatorial aspirant proclaimed Tuesday. But, like Rendell, Kaine had no trouble forgiving Clinton's lies. Nor did he flinch at the extramarital fibs of former Virginia Gov. Chuck Robb.

Robb, you might recall, was scrutinized in the 1980s for being at parties where cocaine was used. Robb denied knowing about the drugs and said he didn't even know what cocaine looked like. In 1991, NBC News reported further details about the parties and included an interview with Tai Collins, the 1983 Miss USA, who said that she'd had an affair with Robb and that Robb's lawyers had tried to bully her into silence. Robb firmly denied the allegations: "I did not commit adultery with Tai Collins; I did not engage in any sexual activity with her; I did not have an affair with her … All stories to the contrary are categorically false." Robb's office added that "no affair ever took place—platonic, romantic, sexual or otherwise." Instead, Robb claimed that she had merely met him in a hotel room, shared a bottle of wine with him, and given him a nude massage.