While 45% of pre-retirees say they expect to rely on 401(k) plans or individual retirement accounts to fund their retirements, the number is shrinking, according to a new Gallup poll.

A growing number of pre-retirees say they expect Social Security payments to be a major source of income in retirement, despite warnings that Social Security may not have enough new income to pay all the retired Baby Boomers.

"The 35% of non-retirees who say Social Security will be a major source of income in their retirement is the highest Gallup has measured since 2001, the first year the annual Gallup Economy and Personal Finance survey was conducted," Gallup said. "Prior to 2008, between 25% and 29% of non-retired Americans expected Social Security to be a major source of retirement funding, but that number has been at or above 30% in each of the last three years.

Gallup and other surveys have noted that there is a noticeable gap between pre-retirees retirement expectations and the experiences of current retirees.