WASHINGTON — President Barack Obama's offer to slow the growth of Social Security benefits would force fellow Democrats in Congress to abandon promises to shield the massive retirement and disability program from cuts as part of negotiations to avoid the year-end fiscal cliff.

Both Senate Majority Leader Harry Reid, D-Nev., and House Minority Leader Nancy Pelosi, D-Calif., pledged not to touch Social Security as part of deficit reduction talks. Now that Obama and House Speaker John Boehner, R-Ohio, have agreed to a new measure of inflation that would reduce annual cost-of-living adjustments, or COLAs, for Social Security and other government programs, Democrats are reluctant to call it a deal-breaker.

As Obama and Boehner continued to haggle over how much to raise taxes and cut spending, White House Press Secretary Jay Carney called the new inflation measure a technical adjustment designed to make inflation estimates more accurate, and he emphasized it's Republicans who want it.