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Summers: The 2016 presidential campaign should focus on middle class
01:37 - Source: CNN
Nashua, New Hampshire CNN  — 

Leading Republican presidential contenders aren’t shying away from proposals to overhaul Social Security and Medicare—once considered untouchable third rails of American politics.

Chris Christie, Marco Rubio and Jeb Bush all told audiences at the Republican Leadership Summit in New Hampshire this week that the United States must rein in spending on those programs, largely by raising the minimum age of eligibility.

Their comments set up a potential clash with Democratic front-runner Hillary Clinton—and pose a fresh test of whether younger generations are willing to side with a party that proposes big changes to decades-old programs.

“There is no political advantage to talking about those issues,” Christie said earlier this week. “The reason you talk about them is because you want to really make suggestions that will help solve the problems that our country confronts.”

RELATED: Christie spells out entitlement reform plan

Christie, the New Jersey governor who’s flagging in the polls, ushered in the debate when he unveiled a proposal to overhaul entitlement programs that’s meant to be a centerpiece of his campaign.

It’s an effort to play up Christie’s brusque, straight-talking style—on display as he honed in on the issue at two town hall meetings he held in New Hampshire, insisting that other contenders’ claims that they’d beef up national security are nothing but talk until they address Social Security and Medicare, too.

His means-testing proposal would phase out Social Security benefits for those earning more than $80,000 in annual retirement income, and eliminate them for those who bring in more than $200,000. He’d raise the retirement age to 69 for Social Security and 67 for Medicare, and impose a similar sliding scale for the health insurance program’s benefits, requiring wealthier seniors to cover more of their premiums.

Rubio, the Florida senator, was asked about Christie’s proposal at the summit, and quickly said he agreed that changes, like increasing the retirement age, are necessary.

“The math is unmistakable,” Rubio said.

When Social Security was created under President Franklin D. Roosevelt, there were 16 workers for every eligible retiree, Rubio said. Today, it’s three workers to each recipient.

“If we want to reform these programs in a way that doesn’t impact anyone like my mother—people currently in the program or about to retire—it will require my generation and your generation to accept that our Social Security and our Medicare is still going to be the best in the world, but it’s going to look different than our parents’ Social Security and their Medicare,” he said.

Bush, meanwhile, weighed in Friday morning at an event in Manchester, backing a higher eligibility age.

“I think we need to raise the retirement age, not for people that are already nearing, receiving Social Security, or already on it, but raise it gradually, over a long period of time for people that are just entering the system. And I think we need to do that in relatively short order,” he said.

RELATED: GOP presidential hopefuls woo party faithful in New Hampshire

Other Republicans also could wade into the debate.

The New Hampshire Republican Party is hosting its First-in-the-Nation Leadership Summit at the Crowne Plaza Hotel in Nashua. Christie, Rubio and Bush took the stage on Friday, the first day. Kentucky Sen. Rand Paul spoke Saturday morning, and was scheduled to be followed by Texas Sen. Ted Cruz, Wisconsin Gov. Scott Walker and several other White House aspirants.