Hoping a new charm offensive will seal an elusive grand bargain with House Speaker John Boehner, President Obama is banking that his proposal to index Social Security benefits according to a “chained” Consumer Price Index will be a game changer.

The debt-obsessed Simpson-Bowles political establishment is cheering, but make no mistake: There is absolutely nothing in Obama’s 2014 budget for any true Republican to love. Especially not his plan for cutting Social Security, which is nothing more than a cleverly baited political trap.

Obama knows that the conservative think tanks will jump at his plan to impose the heavy hand of a “chained CPI” to bend the long-term arc of Social Security spending. But if the GOP takes the bait — and middle-class retirees suffer their first-ever benefit cut — liberal activists will still blame and pummel the GOP in the 2014 midterms. And nothing would stop a future Democratic Congress from reinstating the old formula.

Because it has nothing to do with our fiscal problems, Social Security shouldn’t even be on the table. According to its Board of Trustees’ 2012 report, the program’s outlays currently represent 5 percent of GDP and are projected to rise to about 7 percent in the 2030s before plateauing around 6 percent for the last half of the century. It makes perfect economic and budgetary sense for House Republicans to tell Obama that they’re sticking with the most voter-friendly part of House Budget Committee Chairman Paul Ryan’s “Path to Prosperity”: no changes to Social Security.

But there are other reasons to oppose an accounting gimmick that sounds like a 1980s horror movie — “The Washington Chained-CPI Massacre.” As Ramesh Ponnuru of National Review has warned, the chainsaw moves in the other direction, too: It would burden the working-age population by reducing upward adjustments in income-tax brackets as prices rise.

True to his game, Obama is pairing his Social Security gambit with a bevy of new levies above and beyond those he forced on Republicans in early January. That’s a terrible recipe for an economy struggling to deliver full-time work for at least 23 million breadwinners.

So the GOP needs to stand firm not only in opposition to Social Security cuts but also against hiking taxes or closing so-called loopholes that help the middle class, particularly young married parents.

On this point, Grover Norquist is dead right: The federal government doesn’t need another nickel, especially until every “diversity counselor,” every anti-American multicultural initiative, and every last abortion accomplice or institutional pimp like Planned Parenthood is fully defunded.

Consequently, Republicans need to shift attention to the sacred cows of current overspending, not middle-class earned benefits. These boondoggles include foreign aid to countries and entities like China, North Korea, Egypt, and the Palestinians, as well as all the wasteful grant-making by federal agencies, especially the Departments of Health & Human Services and Education.

Not to mention the biggest fiscal drain of all: means-tested public-welfare expenditures embedded throughout several federal departments — now pushing an astounding $1 trillion a year counting state matching funds — including Obama’s newfound interest in expanding Head Start-like pre-K, the latest rent-seeking by feminists under the pretense of “early education.”

By zeroing in on the real fat in the budget, Republicans can demonstrate all they claim to be: the party of Middle America. And by grafting opposition to any Social Security cuts onto its long-standing pledge of not raising taxes, the Party of Lincoln could turn the tables on Obama and find a way out of the wilderness.

Robert W. Patterson served as a speechwriter in the George W. Bush administration and as a welfare policy advisor in the administration of Pennsylvania Gov. Tom Corbett. Follow him on Twitter.