WASHINGTON — Cutting federal health and retirement spending has long been at the top of the Republican agenda. But with Republicans in striking distance of winning the Senate, they are suddenly blasting the idea of trimming Social Security benefits.

The latest attack came in Georgia, where the National Republican Campaign Committee posted an ad last week accusing Democratic Rep. John Barrow of “leaving Georgia seniors behind” by supporting “a plan that would raise the retirement age to 69 while cutting Social Security benefits.”

Crossroads GPS, the conservative nonprofit group founded by GOP strategist Karl Rove, has run similar ads against Democrats including Sen. Kay Hagan of North Carolina, Sen. Mark Pryor of Arkansas and Rep. Scott Peters of California. Crossroads accused Hagan of supporting a “controversial plan” that “raises the retirement age.”

Pryor’s opponent, Rep. Tom Cotton, meanwhile, is one of at least three Republican candidates in competitive Senate races who has released cheery ads promising to protect Social Security. In Colorado, Republican Rep. Cory Gardner appears in a new ad with his “Grandma Betty” and vows to “honor every penny we promised today’s seniors” – a pledge that seems to conflict with demands by Republican congressional leaders for a less-generous inflation formula to calculate seniors’ cost-of-living increases.

CHARGES OF HYPOCRISY

Older voters typically dominate the electorate in non-presidential years, so the resort to Social Security as an issue in the Nov. 4 midterms is hardly surprising. But what has drawn attention – and charges of hypocrisy –is the decision by Republican groups to attack Democrats for supporting conservative ideas in a proposed “grand bargain” on the budget drafted by Democrat Erskine Bowles and former Republican Sen. Alan Simpson of Wyoming.

Once venerated in both parties as a good-faith proposal, the Bowles-Simpson plan calls for political compromise to rein in the $17.9 trillion national debt, which was dangerously elevated by the recent recession. Republicans would raise taxes, the theory goes, in exchange for Democrats cutting health and retirement spending. Among its proposals: trim Social Security benefits for well-off seniors, raise the retirement age to 69 by 2075 and adopt the new inflation measure, known as the chained Consumer Price Index, or chained CPI.

Both Crossroads GPS and NRCC, the party’s campaign arm for House races, have cited Democrats’ support for Bowles-Simpson as the basis of their charges on Social Security, though many Republicans – including Rove – have criticized President Obama for failing to support the Bowles-Simpson package.

A spokesman for Crossroads GPS declined to comment. NRCC spokeswoman Andrea Bozek also declined to discuss the ad targeting Barrow, saying by email only that “our ads are a comprehensive and accurate reflection of John Barrow’s record.”

DEFENDING MODERATE DEMOCRAT

Bowles and Simpson have responded with rebukes in local op-ed pages, most recently under the headline, “Barrow is brave.”

“We need members of Congress who have the guts to ignore these scare tactics and look at the substance of real solutions that will help get our great nation back on track,” the pair wrote in the Statesboro (Ga.) Herald in defense of Barrow, a moderate Democrat and five-term incumbent locked in a tight race with Republican businessman Rick Allen.

Reached by phone, Simpson declined to criticize the GOP groups. “How can you be disappointed?” he said. “It’s savagery out there.”

Former Republican Sen. Judd Gregg of New Hampshire, an original member of the 2010 debt-reduction commission led by Bowles and Simpson, was more direct.

“It really is inappropriate for Republicans to attack people who stand up for entitlement reforms, especially hard reforms to Social Security and Medicare along the lines of what Simpson-Bowles proposes,” said Gregg, who now serves as chairman of a debt-reduction organization called Fix the Debt.

But, he said, “In elections, you do whatever you think will work.”

There are obvious advantages to accusing one’s political opponent of monkeying with Social Security. A new survey out Thursday from the National Academy of Social Insurance found overwhelming support for the program among voters in both parties, with 69 percent of Republicans agreeing “it is critical to preserve Social Security benefits . . . even if it means increasing the Social Security taxes.”

More than 70 percent of Republicans and 92 percent of Democrats agreed that top earners should pay Social Security taxes on their entire earnings, not just wages under $117,700. Meanwhile, three-quarters of those surveyed oppose raising the retirement age and reducing cost-of-living increases, for example, by adopting the chained CPI.

Liberals are hailing the outpouring of Republican affection for Social Security, arguing that it reflects a broader consensus that government austerity is the wrong response to the sluggish economy.

“What gave Bowles-Simpson credibility was the fact that the president was after this grand bargain. Well, he is no longer trying to achieve a grand bargain,” said Roger Hickey, co-director of the liberal Campaign for America’s Future. “So now Bowles-Simpson is simply a way that politicians went on the record as being in favor of cutting Social Security and Medicare. And now it’s something that can be used against them.”