The National Active and Retired Federal Employees Association organized a news conference outside the Capitol last month to ask lawmakers to vote against switching to chained CPI.

"Raising taxes on the wealthy is not a trade-off for hurting our nation's seniors," said Jessica Klement, a lobbyist for the organization.

Retirees say changing the inflation yardstick seems like a bait and switch.

"We make life decisions based on what we know the annuities will be and what seems sort of unfair is changing the rules after you make those life decisions and after you are retired," said Rick Swenson, 60, who retired last year as an administrative officer with the Department of Agriculture.

Using an online calculator created by the National Active and Retired Federal Employees Association, the Catonsville man figured that he would receive $95,000 less over 20 years under chained CPI.

"I'm like everybody else," he said. "I want to see a reduction in our deficit. Everybody will have to do their part. I just hope that it's fair and equal contribution."

Miller, the retired patent lawyer, said consumers' buying behaviors should not be a factor in calculating inflation.

"I could move to a high-cost area and I would not expect the government to increase my pension because I moved to a high-cost area," he said. "And I would not expect them to pay me less because I chose to move to a low-cost area.

"If the government is looking to save money, just be honest about it rather than saying this is a better way to measure inflation."

Goldwein said chained CPI would protect Social Security by reducing the program's long-term financial shortfall by more than 20 percent..

That's one reason Nick Troiano, 24, likes the inflation index. Last year, he co-founded The Can Kicks Back to urge lawmakers to stop delaying and address the national debt now.

"Social Security itself is on an unsustainable path," Troiano said. "In the next 20 years, there would be a 23 percent benefit cut for everyone if we don't do something about it.

"Chained CPI is a sensible reform. It's a technical change that would strengthen the program and help assure that Social Security is solvent for my generation."

The campaign, which is staffed by millennials, takes its message to college campuses.

"We tell our supporters the most important phone call they can make is not to elected officials, it's to their grandparents," he said. "The solution is not just bipartisanship, but generational. It's all the generations working together for a fair solution."