AUGUSTA, Maine — As efforts to broaden health care coverage sputter in Congress, a survey released Wednesday in Maine said 11 percent of the state’s adults lack health insurance, and nearly one in five of those with insurance are afraid of losing the coverage they have.

The survey by Market Decisions of Portland says the percentage of uninsured is slightly higher, 13 percent, for adults ages 18 to 64. The survey, which was conducted Jan. 20 to Feb. 4, also shows that among Maine’s uninsured adults, 47 percent have been without coverage for more than five years.

Trish Riley, director of Gov. John Baldacci’s Office of Health Policy and Finance, said the figures were consistent with what census data show. Riley said Maine’s uninsured rate has declined marginally over the past several years and Maine remains among the states with the lowest uninsured rates.

“The surprise here is that people are frightened about the cost,” Riley said.

Of those who are uninsured, 49 percent said the cost for health insurance coverage was too high, and 26 percent said health insurance that’s available simply wasn’t worth the cost. Thirty-five percent of the uninsured Mainers surveyed said their employer either did not offer health insurance coverage or had dropped coverage for employees.

The survey also shows that people are putting off needed medical care because of the cost. Ten percent of those responding said they did not get needed medical care from a doctor or surgery during the past year because of the cost, and 25 percent did not get needed dental care.

Among the insured Mainers, 18 percent said they were concerned they may lose their health insurance during the next 12 months because of such things as premium cost increases, the impact of health care reform and a loss of employment.

Market Decisions Research Director Brian Robertson said the percentage of Maine’s adult population lacking health insurance remains below the national average. The national Centers for Disease Control and Prevention says about 15 percent of Americans had no health insurance in 2008.

In the other northern New England states, Vermont’s uninsured percentage was 7.6 percent in 2009. In New Hampshire, the uninsured rate for adults ages 19-64 is 14 percent, and 5 percent for children 18 and under.

The survey comes out as further action is pending on bills passed by the U.S. House and Senate that seek to lower the uninsured rate.

Market Decisions surveyed 401 Maine residents 18 and older. Results have an error margin of 5 percentage points. Market Decisions, which conducts surveys on a variety of issues, said its poll was taken in the public interest and not for any public or private organization.