NBC’s “Meet the Press” hosted a discussion between the two major party chairs — the DNC’s Debbie Wasserman Schultz and the RNC’s Reince Priebus — and right off the bat, host David Gregory wanted to talk at length about Rep. Anthony Weiner (D-N.Y.). Priebus stuck to fairly predictable talking points, complaining that House Democratic leaders did exactly what the RNC wanted them to do, but didn’t do it fast enough to make Priebus happy. “This is a question of leadership,” he said.

Wasserman Schultz responded by bringing up the one subject the RNC really doesn’t want to talk about.

“What Reince is saying doesn’t pass the straight face test, from a chair of a party who — none of whose leaders called for Senator Vitter, who actually broke the law, to resign, who is still serving in office. Hired prostitutes and evaded the truth. Chairman Priebus was chairman when Senator Ensign was also embroiled in unethical, unacceptable and probably illegal conduct, and he did not call for Senator Ensign’s resignation.”

Priebus noted that Ensign resigned, prompting DWS to remind him, “But you never called for his resignation, so it’s a double standard and it’s unacceptable.”

When the RNC chairman insisted, for some reason, “It’s not a double standard,” the host noted that “nobody” called on Vitter to resign and asked where the line is. Priebus argued:

“Well, listen. I mean, Senator Vitter, that’s a, that’s a five-year-old story. Chris Lee, how long did he last? About 30 seconds. How long — Senator Ensign resigned within six weeks of me becoming chairman.”

He then changed the subject.

This is the most detailed response Priebus has given to date, so let’s look at the angles one at a time. First, Vitter is a “five-year-old story.” That’s true. It’s also irrelevant. In five years, the Anthony Weiner matter will be a five-year-old story, too.

Vitter ran as a right-wing family-values conservative then hired prostitutes, even arranging a rendezvous with a hooker from the floor of the House. No one called for his resignation, no one called on his allies to return money he’d given them. Priebus argued yesterday the Weiner controversy is a test of Democratic “leadership.” So, where’s the Republican leadership on Vitter? His misdeeds don’t look any better with the passage of time.

Next, Chris Lee did resign, but it’s not because Republicans showed great “leadership”; it’s because there was evidence that Lee was into transsexuals and cross-dressers, and quit before the additional information could come out.

And finally, Ensign resigned two years after his scandal broke, not because of pressure from the party, but because the Republican saw quitting as a way to avoid testifying under oath. Like Vitter, Republicans never called for Ensign’s ouster, and never argued that other Republicans should return donations Ensign made to them.

As Wasserman Schultz demonstrated, Dems see this as something of a trump card — if Weiner has to go, then Republicans who engaged in even more serious scandals should be held to an identical standard. Until GOP officials can come up with a coherent response to this, the argument will remain atop the list of Democratic talking points.

Steve Benen

Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.