"Social Security is a bedrock of lifetime financial security for all generations, and it is not in crisis," said Drew Nannis, a spokesman for AARP, which has launched a campaign to preserve and strengthen the government program.
Some 38 million retirees and their dependents receive Social Security benefits. The average monthly payout is $1,175.
An additional 16 million people with disabilities, survivors and dependents also receive monthly benefits.
"We need to come together to find ways to strengthen the program for current and future generations to secure the hard-earned benefits they will be counting on for years to come," Nannis added.
The poll, released Thursday, found that a majority of Americans think Social Security is in need of an overhaul to shore up the program, and that if no changes are made, it will be in trouble.
But at a time of vanishing pensions, shrinking savings and rising health care costs, more than two to one oppose reducing guaranteed benefits for future retirees.
When it comes to other options for changes to Social Security, nearly two-thirds (61 percent) of those surveyed oppose raising the Social Security tax rate while one-third (35 percent) said they support it. A poll in 2005 found similar results.
Support for collecting Social Security on all the money a worker earns, instead of just some of it (up to $107,000 in 2011), has weakened slightly — with 53 percent supporting the increase, down from 56 percent in 2005.
There was increased support for raising the retirement age to 68 for full benefits: 42 percent of those surveyed support that option, 9 percentage points higher than 2005.
Likewise, more people (46 percent) support reducing the benefits paid to people who retire early (36 percent in 2005).
The latest poll comes as some members of Congress have begun discussions on reforming Social Security, Medicare and Medicaid to address the annual federal budget deficit. The nonpartisan Congressional Budget Office says that Social Security does not contribute to the deficit.
The poll surveyed 1,005 adults by telephone in March. It has a margin of error of 3.5 percentage points.
Carole Fleck is an editor at the AARP Bulletin.