Of 2,020 U.S. adults polled, 53 percent of those between the ages of 30 and 64 were worried their money would run out before they died, Gallup said.

Older people 65 and above were less apt to be worried, as were those ages 18-to-29.

In the younger group, 43 percent worried they would outlive their money, while in the older group 31 percent worried they would.

As a solution, "faced with today's financial squeeze ... many Americans seem to have concluded that one way to address their fears is to delay their retirement," the survey said.

Forty-five percent of U.S. adults now say they worry they will have to postpone the retirement they had originally planned, Gallup said.

The survey, conducted Jan. 30 through Feb. 2, has a margin of error of plus or minus 3 percent.