Following up on an item from yesterday, the Progressive Change Campaign Committee launched an ad this week targeting New Hampshire Rep. Charlie Bass (R), noting his vote to end Medicare. The National Republican Congressional Committee decided to make this something of a test case — the party argued the Medicare claim is false and demanded that the station pull the ad from the airwaves.

Substantively, the Republicans’ claim is absurd, but if the NRCC was successful anyway, the party would use this as leverage to block the campaign speech that makes Republicans look bad elsewhere.

Late yesterday, the network announced its response to the NRCC’s demands: No.

Comcast Boston has rebuffed the NRCC’s demand that it yank an ad being run by liberal groups that attacks GOP Rep. Charlie Bass for supporting the GOP plan to “end Medicare.” The NRCC argued in a long letter that the claim is false.

“We are continuing to air the ad,” Chris Ellis, a spokesman for Comcast’s ad sales division, tells me. “We’ve reviewed the materials provided by the NRCC and the documentation provided by the advertisers, and we’ve decided that the ad does meet our guidelines.”

In fairness to the NRCC, it’s very hard to get ads pulled, and both sides try to do this all the time with little success. Comcast’s decision, however, is likely to embolden Dems to stick by their claim that the GOP plan “ends Medicare.”

In general, I’m fairly comfortable with stations declining political ads that can proven to be patently, demonstrably false. But in this case, the PCCC message is entirely fair and accurate — the plan from congressional Republicans is to end Medicare and replace it with a privatized voucher scheme. Comcast Boston made the right call.

Of course, by throwing such a fit over this, Republicans also appear to be telegraphing a weakness: the party’s polling must show that the “end Medicare” message is quite damaging or Republicans wouldn’t be fighting so hard to prevent people from hearing it.

This should lead Dems to start using the line even more.

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.