Blame the economy, the government and the cruddy job market: Those are among the top reasons one in five Americans decided last year that they’ll need to work longer than expected.

The 2011 Retirement Confidence Survey, an annual report conducted by the Employee Benefit Research Institute, found that 20 percent of Americans had decided in the past year that they will have to retire later than they thought they would.

For 36 percent of those who decided in the past year to postpone retirement, the poor economy was to blame.

Another 16 percent said they expect to retire at a later age because of a lack of faith in the government and/or Social Security. Fifteen percent cited a change in their employment situation.

Other reasons for delaying retirement included not having enough money, stock market losses and health care costs.

In general, the EBRI said there has been a gradual rise in the age at which people plan to retire. Just under one-fourth of all workers in the 2011 survey plan to retire before age 65. In 1991, half of all workers planned to retire before age 65.

The weak economy appears to have exacerbated the trend. In both 2009 and 2010, about one-quarter of those surveyed said they expected to retire later than planned.  

The 21^st annual retirement survey included 1,258 Americans over age 25 and was conducted in January.