WASHINGTON -- The refusal by about half the states to expand Medicaid will leave millions of poor people ineligible for government-subsidized health insurance under President Obama's health care law even as many others with higher incomes receive federal subsidies to buy insurance.
Starting next month, the administration and its allies will conduct a nationwide campaign encouraging Americans to take advantage of new high-quality affordable insurance options. But those options will be unavailable to some of the neediest people in states like Texas, Florida, Kansas, Alabama, Louisiana, Mississippi and Georgia, which are refusing to expand Medicaid.
More than half of all people without health insurance live in states that are not planning to expand Medicaid.
People in those states who have incomes from the poverty level up to four times that amount ($11,490 to $45,960 a year for an individual) can get federal tax credits to subsidize the purchase of private health insurance. But many people below the poverty line will be unable to get tax credits, Medicaid or other help with health insurance.
Sandy Praeger, the insurance commissioner of Kansas, said she would help consumers understand their options. She said, however, that many of "the poorest of the poor" would fall into a gap in which no assistance is available.
The Kansas Medicaid program provides no coverage for able-bodied childless adults. And adults with dependent children are generally ineligible if their income exceeds 32 percent of the poverty level, Ms. Praeger said.
In most cases, she said, adults with incomes from 32 percent to 100 percent of the poverty level ($6,250 to $19,530 for a family of three) "will have no assistance." They will see advertisements promoting new insurance options, but in most cases will not learn that they are ineligible until they apply.
Administration officials said they worried that frustrated consumers might blame President Obama rather than Republicans like Gov. Rick Perry of Texas and Gov. Bobby Jindal of Louisiana, who have resisted the expansion of Medicaid.
The Congressional Budget Office estimates that 25 million people will gain insurance under the new health care law. Researchers at the Urban Institute estimate that 5.7 million uninsured adults with incomes below the poverty level could also gain coverage except that they live in states that are not expanding Medicaid.
In approving the health care law in 2010, Congressional Democrats intended to expand Medicaid eligibility in every state.
But the Supreme Court ruled last year that the expansion was an option for states, not a requirement. At least 25 states -- mainly those with Republican governors or Republican-controlled legislatures -- have balked at expanding the program, in part because of concerns about long-term costs.
Several Republican governors, like Rick Scott in Florida, wanted to expand Medicaid, but met resistance from state legislators.
Mr. Obama and administration officials, including Kathleen Sebelius, the secretary of health and human services, plan to fly around the country this summer promoting the health care law to a public largely unaware of the new insurance options.
Bee Moorhead, the executive director of Texas Impact, an interfaith group that favors the expansion of coverage, said: "A lot of people will come in, file applications and find they are not eligible for help because they are too poor. We'll have to tell them, 'If only you had a little more money, you could get insurance subsidies, but because you are so poor, you cannot get anything.'
"That's an odd message, a very strange message. And if people are sick, they will be really upset."
In Atlanta, Amanda Ptashkin, the director of outreach and advocacy at Georgians for a Healthy Future, a consumer group, said: "Hundreds of thousands of people with incomes below the poverty level would be eligible for Medicaid if the state decided to move forward with the expansion of Medicaid. As things now stand, they will not be eligible for anything. What do we do for them? What do we tell them?"
Jonathan E. Chapman, the executive director of the Louisiana Primary Care Association, which represents more than two dozen community health centers, described the situation in his state this way: "If the breadwinner in a family of four works full time at a job that pays $14 an hour and the family has no other income, he or she will be eligible for insurance subsidies. But if they make $10 an hour, they will not be eligible for anything."
Bruce Lesley, the president of First Focus, a child advocacy group, said: "In states that do not expand Medicaid, some of the neediest people will not get coverage. But people who are just above the poverty line or in the middle class can get subsidized coverage. People will be denied assistance because they don't make enough money. Trying to explain that will be a nightmare."
The subsidies, for the purchase of private insurance, will vary with income and are expected to average more than $5,000 a year in 2014 for each person who qualifies.
Evan S. Dillard, the chief executive of Forrest General Hospital in Hattiesburg, Miss., said the eligibility rules would be "very confusing to working poor individuals in this, the poorest state in the country."
Starting in January, most Americans will be required to have health insurance and will be subject to tax penalties if they go without coverage. However, the penalties will not apply to low-income people denied access to Medicaid because they live in states that chose not to expand eligibility.
Deborah H. Tucker, the chief executive of Whatley Health Services, a community health center in Tuscaloosa, Ala., said it was wonderful that many uninsured people would gain coverage, but "tragic that some of the most vulnerable, lowest-income people" would be excluded.
Ms. Tucker said her clinics cared for nearly 30,000 patients a year, including 16,000 who were uninsured. More than 75 percent of the uninsured patients have incomes below the poverty level and are unlikely to qualify for Medicaid or subsidies, she said.
The Obama administration is urging people who "need health insurance" to report their telephone numbers and e-mail addresses to the government via a Web site, healthcare.gov, so they can be notified of new insurance options.
Consumers will not necessarily know whether they are eligible for premium tax credits, Medicaid or the Children's Health Insurance Program.
So if a person applies for one program, federal and state officials will check eligibility for all three.
People who are currently eligible but not enrolled may sign up for Medicaid, even in states that do not expand the program.
Still, Roy S. Mitchell, the executive director of the Mississippi Health Advocacy Program, a nonprofit group that supports the expansion of Medicaid, said "there's going to be a huge void" as many uninsured poor people find that they are not eligible for Medicaid or insurance subsidies.
"There will be an outcry," Mr. Mitchell said. "It may bolster our advocacy efforts."
The history of Medicaid shows that it took several years for some states to sign up in the 1960s, raising the possibility that additional states may decide to expand eligibility in coming years.
This article originally appeared in The New York Times.