WASHINGTON (AP) – If the uninsured were a political lobbying group, they’d have more members than AARP. The National Mall couldn’t hold them if they decided to march on Washington.

But going without health insurance is still seen as a personal issue, a misfortune for many and a choice for some. People who lose coverage often struggle alone instead of turning their frustration into political action.

Illegal immigrants rallied in Washington during past immigration debates, but the uninsured linger in the background as Congress struggles with a health care overhaul that seems to have the best odds in years of passing.

That isolation could have profound repercussions.

Lawmakers already face tough choices to come up with the hundreds of billions it would cost to guarantee coverage for all. The lack of a vocal constituency won’t help. Congress might decide to cover the uninsured slowly, in stages.

The uninsured “do not provide political benefit for the aid you give them,” said Robert Blendon, a professor of health policy and political analysis at the Harvard School of Public Health. “That’s one of the dilemmas in getting all this money. If I’m in Congress, and I help out farmers, they’ll help me out politically. But if I help out the uninsured, they are not likely to help members of Congress get re-elected.”

The number of uninsured has grown to an estimated 50 million people because of the recession. Even so, advocates in the halls of Congress are rarely the uninsured themselves. The most visible are groups that represent people who have insurance, usually union members and older people. In the last election, only 10 percent of registered voters said they were uninsured.

The grass-roots group Health Care for America Now plans to bring as many as 15,000 people to Washington this year to lobby Congress for guaranteed coverage. Campaign director Richard Kirsch expects most to have health insurance.

“We would never want to organize the uninsured by themselves because Americans see the problem as affordability, and that is the key thing,” he said.

Besides, added Kirsch, the uninsured are too busy scrambling to make ends meet. Many are self-employed; others are holding two or three part-time jobs. “They may not have a lot of time to be activists,” he said.

Vicki and Lyle White of Summerfield, Fla., know about such predicaments. They lost their health insurance because Lyle had to retire early after a heart attack left him unable to do his job as a custodian at Disney World. Vicki, 60, sells real estate. Her income has plunged due to the housing collapse.

“We didn’t realize that after he had the heart attack no one would want to insure him,” said Vicki. The one bright spot is that Lyle, 64, has qualified for Medicare disability benefits and expects to be getting his card in July.

Research shows that nearly half of those who lose coverage find other health insurance in four months or less. That may be another reason the uninsured have not organized an advocacy group. At least until this recession, many have been able to fix the situation themselves.

“The uninsured are a moving target,” said Cathy Schoen, a vice president of the Commonwealth Fund, a research group that studies the problems of health care costs and coverage.

But even if gaps in coverage are only temporary, they can be dangerous. “Whenever you are uninsured, you are at risk,” said Schoen. “People don’t plan very well when they are going to get sick or injured.”

Indeed, the Institute of Medicine, which provides scientific advice to the government, has found that a lack of health insurance increases the chances of bad outcomes for people with a range of common ailments, from diabetes and high blood pressure to cancer and stroke. Uninsured patients don’t get needed follow-up care, skip taking prescription medicines and put off seeking help when they develop new symptoms.

Such evidence strengthens the case for getting everybody covered right away, Schoen said. But she acknowledges the politics may get tough. “It certainly has been a concern out of our history that unorganized voices aren’t heard,” she said.