The other day, I noted that Karl Rove’s Crossroads GPS is up with a new ad that slices and dices Dem Senator Mark Pryor’s quotes to create the impression he supports raising the Social Security retirement age in ways that should frighten today’s seniors. Just as they have in the last two cycles — in which Republicans have built national campaigns around dishonest attacks on Obamacare’s provider-side cuts to Medicare — this ad shows Republicans once again hitting Dems from the left on entitlements.

Now Rove’s Crossroads is back with another ad that does pretty much the same thing, this one hitting Senator Kay Hagan in North Carolina over Social Security’s retirement age. The spot, which is backed by more than $1 million, says Hagan is a “big believer” in a “controversial plan” that “raises the retirement age,” while the words “raises Social Security retirement age” flash on the screen. It also claims the plan Hagan supports “increases out-of-pocket Medicare costs.”

Yes, it appears Rove’s Crossroads is attacking Hagan for saying nice things about the Simpson Bowles debt reduction plan, which squeezes seniors by cutting Social Security and Medicare benefits.

The citation in the ad is this Raleigh News and Observer article quoting Hagan as follows: “I am a big believer in what Erskine Bowles and Alan Simpson did on their fiscal commission.”

The Hagan campaign hit back by arguing she has never endorsed raising the retirement age and has opposed Social Security benefits cuts. Indeed, the article cited only shows her generally praising the plan’s goal of reducing the deficit.

It is remarkable to watch Rove’s group try to position multiple Democratic Senators as the real threat to social insurance for the elderly, for the third straight cycle — and even more intriguingly, to use Simpson Bowles to do so. After all, Simpson Bowles is still widely treated as a paragon of unimpeachable fiscally responsible centrism, and Dems have long been pilloried by Beltway fiscal scold types for refusing to embrace its sanctified prescriptions for deficit reduction.

Indeed, this sort of Crossroads rhetoric should outrage fiscal conservatives. As Philip Klein put it in a post slamming Crossroads’ ad against Mark Pryor: “if Republicans want to be a limited government party, they have to be making the case for reforming entitlements — not running ads attacking Democrats from the left.”

The larger context here, as David Frum explains in an essay for Foreign Affairs, is the increasing GOP reliance on elderly voters, and the tension that creates with the GOP’s goal of limited government, given that the elderly are “the most government-dependent segment of the population.” Frum explains that this represents a demographic and cultural strategy rooted in an exploitation of Baby Boomers’ fiscal anxieties as a crucial ingredient of GOP electoral success:

Boomers’ conservatism is founded on their apprehension that there’s not enough to go around — and on their conviction that what little resources there are should accrue to them…Republicans have responded to boomers’ fears by reinventing themselves as defenders of the fiscal status quo for older Americans — and only older Americans.

Jonathan Chait adds that this leaves no room for Republicans to craft fiscal policies that might broaden the GOP’s appeal to everyone else:

The Republican Party constructed a geriatric trap for itself. Just how it will escape is hard to see. It is a small-government party whose base is wedded to the programs that constitute a large and growing share of government. The inability to touch the benefits of any old person, in combination with its still-extant support for defense and fanatical opposition to tax hikes in any form, have driven Republicans to propose massive cuts to the small share of government that benefits struggling workers. This priority has, in turn, saddled the GOP with the (correct) image of hostility toward the unfortunate.

Indeed, in the North Carolina and Arkansas Senate races, the GOP candidates are simultaneously running on repeal of Obamacare’s benefits to millions, even as the draconian Paul Ryan budget remains the GOP’s fiscal and economic lodestar.

Of course, Republicans may well get away with attacking Dems from the left on social insurance, and win the Senate. But just as the GOP’s lurch to the right on immigration may successfully crank up the base’s enthusiasm heading into the midterms while exacerbating the party’s long term Latino problem, this gambit on entitlements could prove another area where the party can win the Senate even as it does nothing to address its longer-term challenges.

Greg Sargent writes The Plum Line blog, a reported opinion blog with a liberal slant -- what you might call “opinionated reporting” from the left.