A total of 28,100 Connecticut residents — roughly the population of Windsor — will lose their health coverage in 2009 as a result of losing their jobs, according to an estimate by Families USA to be released in a report today.

By the end of the year, the consumer advocacy group projects that Connecticut will have 303,000, or 14.1 percent of all adults between the ages of 19 and 64 without health care benefits. That compares with 275,600, or 12.9 percent, in 2008.

Almost all the increase is due to job loss, according to the report.

"That's a significant number if you look at it in terms of lives," said Janet Davenport, a spokeswoman for the Universal Health Care Foundation of Connecticut. "Twenty-eight thousand. That's a lot of lives. And we know it is taking longer in this economy for people to find jobs with good health care benefits."

The report comes a day after the U.S. Senate's finance committee passed a health care reform bill, legislation that could expand coverage to millions who lack it. The legislation could include increased Medicaid benefits that would aid the unemployed and, in Connecticut, could cut the ranks of uninsured adults by a third, some advocates say.

Nationally, 37 million working-age adults were uninsured, or 20 percent, compared with 41 million, or 22 percent, in 2008, the report says.

The projections used a formula developed by the Urban Institute to measure loss of coverage based on the rising unemployment rate.

In Connecticut, the unemployment rate has risen from 7.1 percent at the end of 2008 to 8.1 percent in August, the most recent month available.

Some workers can temporarily continue their health benefits through their employers when their lose their jobs through the COBRA program. This year, Congress approved subsidizing 65 percent of those costs to aid the unemployed. The program expires as of Dec. 31, and today's report could add more impetus to extending it.

But even with the subsidy, some families can't afford the coverage, said Ellen Andrews, executive director of the Connecticut Health Policy Project, a consumer advocacy group.

"Often that is still higher than what they were paying when they were employed," said Andrews, who added that Medicaid expansion could eventually cut the number of uninsured by 100,000.