The number of Americans who lack health insurance continued to increase last year, climbing to 44.3 million in spite of a prosperous economy and recent government efforts to expand coverage.

The ranks of the uninsured grew by about 1 million in 1998, according to figures to be released today by the Census Bureau, which show the proportion of people in the United States without coverage was still one in six. The figures highlight an issue that is generating increased concern among voters and attracting renewed political attention.

The latest portrait of the nation's supply of health insurance -- widely considered a prerequisite of adequate medical care -- contains bright spots. Chief among them, significantly more Americans received insurance from employers last year, including an additional half-million who are poor.

On the other hand, the number of people covered through Medicaid, the government's insurance program for the poor, fell by more than 1 million, probably as a side effect of federal reforms that are moving people off welfare. And the pool of uninsured children remained undiminished, despite a major new federal insurance program, launched in 1997, that was predicted eventually to reach half the 11 million U.S. youngsters who lack coverage.

Taken together, health analysts said, the patterns suggest that the country's unparalleled economic growth, while enabling some people to find better jobs with health benefits, has been unable to reverse a decade-long trend in which more and more people have no help in paying medical bills. "The numbers show what a daunting task it is, without [the government] automatically insuring every American and giving them an insurance card," said Diane Rowland, senior vice president of the Kaiser Commission on Medicaid and the Uninsured.

The new figures, collected as part of the annual Current Population Survey, show that the lack of coverage remains concentrated among certain groups -- people with relatively little education and immigrants. More than one-third of all Latinos are uninsured, far more than any other racial or ethnic group. Lack of coverage remains prevalent among young adults -- who may have jobs without coverage, or decide not to take it.

The figures also show that the number of women who are uninsured increased, but not the number of men -- which analysts interpreted as a reflection of the impact of welfare reform on women who stop receiving government assistance and move into low-end jobs without fringe benefits.

The percentage of people without coverage has declined in several states, but has continued to increase in the District, Maryland and Virginia.

And even as poor Americans have made some progress in obtaining insurance through jobs, fully one-third of them lacked coverage last year.

This fresh evidence of the growing number of uninsured comes as politicians from along the political spectrum are again beginning to view the problem as a ripe political opportunity. Broaching the topic was considered political heresy for several years after President Clinton's failure to remake the nation's health care system in 1994. The Clinton plan would have required everyone to be part of a system of universal health insurance.

Since then, Congress and the administration have taken several limited steps, including a 1996 law to make it easier for people to keep coverage when they change jobs and the Children's Health Insurance Program adopted a year later.

But this year, leading Republicans and Democrats alike are taking up the cause of the uninsured in a more comprehensive fashion -- although the parties' approaches differ. House Speaker J. Dennis Hastert (R-Ill.) last week helped to unveil a GOP bill that would create a variety of tax breaks designed to make coverage more affordable to individuals and small businesses.

Meanwhile, both Democratic presidential candidates have just issued elaborate health care proposals that would extend coverage to millions of children and adults.

"We must redouble our commitment, as an American community, to bring the uninsured into our community of care," Vice President Gore said in releasing his health plan last month. "It is not right that uninsured Americans face illness alone," former New Jersey senator Bill Bradley said as he set forth his own, somewhat more ambitious plan last week.

How to secure health insurance for more Americans has returned to the political agenda at a time when polls show that voters overwhelmingly believe the government should do something to help.

In a new survey conducted by Harvard researchers for the Robert Wood Johnson Foundation, 79 percent of those interviewed said it was "very" or "extremely" important that the federal government pass a law providing coverage for the uninsured. But Americans are less certain about what the government ought to do, with only half favoring a broad attempt to provide insurance to nearly everyone, according to Robert J. Blendon, a health policy professor at the Harvard School of Public Health.

What is clear is that people who lack health insurance tend to get substantially less medical care. One recent survey of U.S. women conducted for the Commonwealth Fund, for instance, found that one in four without coverage said they had forgone treatment they had needed in the previous year, compared with one in 17 women who were insured. And even when they go to a doctor, people without coverage are much more prone not to fill prescriptions for medicine.

Paul Fronstin, senior research associate at the Employee Benefits Research Institute, cautioned that, for people of all income levels, gains in health insurance from employers could prove temporary, because the cost of medical care, steady through much of this decade, is increasing again.

CAPTION: LACKING A HEALTH PLAN (This chart was not available)