US baby boomers are starting to retire, but many are agonizing about their finances and believe they'll need to work longer than they had planned, a new poll finds.

The 77 million-strong generation born in the United States between 1946 and 1964 has clung tenaciously to its youth. Now, boomers are getting nervous about retirement. Only 11 percent say they are strongly convinced they will be able to live in comfort.

A total of 55 percent said they were either somewhat or very certain they could retire with financial security. Yet a substantial 44 percent express little or no faith they'll have enough money when their careers end.

Further underscoring the financial squeeze, one in four boomers still working say they'll never retire. That's about the same number as those who say they have no retirement savings.

The Associated Press-LifeGoesStrong.com poll comes as politicians face growing pressure to curb record federal deficits, and budget hawks of both parties have expressed a willingness to scale back Social Security, the government's biggest program.

The survey suggests how politically risky that would be: 64 percent of boomers see Social Security as the keystone of their retirement earnings, far outpacing pensions, investments and other income.

The survey also highlights the particular retirement challenge facing boomers, who are contemplating exiting the work force just as the worst economy in seven decades left them coping with high jobless rates, tattered home values and painfully low interest rates that stunt the growth of savings.

"I have six kids," said Gary Marshalek, 62, of South Abington Township, Pennsylvania, who services drilling equipment and says he has repeatedly refinanced his home and dipped into his pension to pay for his children's college. His inability to afford retirement "sounds like America at the moment", Marshalek said. "Sounds like the normal instead of the abnormal."

Marshalek was among the 25 percent in the poll who say they plan to never retire. People who are unmarried, earn under $50,000 a year, or say they did a poor job of financial planning are disproportionately represented among that group.

Overall, nearly six in 10 baby boomers say their workplace retirement plans, personal investments or real estate lost value during the economic crisis of the past three years. Of this group, 42 percent say they'll have to delay retirement because their nest eggs shrank.

Though the first boomers are turning 65 this year, the poll finds that 28 percent already consider themselves retired. Of those still working, nearly half want to retire by age 65 and about another quarter envision retiring between 66 and 70.

Two-thirds of those still on the job say they will keep working after they retire, a plan shared about evenly across sex, marital status and education lines, the survey finds. That contrasts with the latest Social Security Administration data on what older people are actually doing: Among those age 65 to 74, less than half earned income from a job in 2008.

"I'm going to keep working after I retire, if nothing else for the healthcare," said Nadine Krieger, 58, a food plant worker from East Berlin, Pennsylvania. Citing $50,000 in retirement savings that she says won't go far, she added, "We probably could have saved more, but you can't when you have a couple of kids in the house."

About six in 10 married boomers expect a comfortable retirement, compared with just under half of the unmarried. Midwesterners are most likely to express confidence in their finances.

"I'm a good planner," said Robert Rivers, 63, a retired New York State employee in Ravena, New York. He still works seasonally for the federal government and collects a modest military pension. A recreational pilot, he says he has scaled back his lifestyle by flying and driving less.

"I'm spending money I have, not spending it and trying to repay it," he said.

Among boomers like Rivers who plan to continue working in retirement, 35 percent say they'll do so to make ends meet. Slightly fewer cite a desire to earn money for extras or to simply stay busy.