When PolitiFact labeled the claim that the GOP voted to end Medicare its “Lie of the Year,” this was seen as a big deal in Washington, because it suggested Republicans might be able to get TV stations to refuse to air Dem ads making the claim against House GOP incumbents. Since this argument will be central to the Dem case in the battle for the House — one that Dems hope to run in ads across the country — that would have been a big setback.

But we’ve now had our first important test case since the PolitiFact decision, and it broke in favor of Dems: Despite GOP complaints, two TV stations have refused to pull the ad.

Earlier this week, the Progressive Change Campaign Committee aired a TV ad, timed to the GOP presidential debate, attacking GOP incumbent Rep. Charlie Bass for voting to “end Medicare.” The Bass campaign sent letters to two stations that air in New Hampshire — WMUR and WHDH — demanding the ads be yanked. Crucially, the Bass campaign repeatedly cited PolitiFact’s Lie of the Year designation to bolster its case.

Both stations refused.

“Our lawyers looked at the ad and concluded it’s within the bounds of robust public debate,” Jeff Barlett, the general manager of WMUR, tells me. “If Charlie Bass and his supporters disagree with this, they’re free to create their own ad and tell their side of the story.”

In the case of WHDH, the station’s lawyers insisted on a very slight tweek to the ad — the new version added an on-screen quote from Paul Krugman agreeing with the “end Medicare” claim — but left the charge completely intact.

“Charlie Bass and the Republicans have now twice asked New Hampshire TV stations not to run the PCCC/DFA television ad holding Congressman Bass accountable for his vote to end Medicare,” says Shelly Hutton, the media buyer for the PCCC and Democracy for America, which is supporting liberal darling Ann McLane Kuster against Bass. “This is an important case study as we enter 2012.”

In other words, Lie of the Year or not, Dems will likely be free to continue to make the claim in ads across the country.