According to one source:
"At least 18 million of the uninsured are under the age of 35 and earn more than enough to purchase health insurance that would cost less than $100 per month. Many of the uninsured qualify for health care coverage through SCHIP, Medicaid or other existing government programs but for whatever reason, about 11 million simply refuse to take advantage of these taxpayer-funded programs. About 2 million of the remaining Americans receive health care as inmates in our prison system since they use jail, penitentiary or prison mailing addresses. Many of the remaining uninsured would never obtain insurance even if it were offered; they are illegal residents, prostitutes and drug addicts. All of these residents currently receive good medical care in emergency rooms or free clinics."
From another:
http://www.cnsnews.com/news/article/52405
Obama Again Inflates Number of Uninsured Americans--Falsely Claiming '46 Million of Our Fellow Citizens Have No Coverage'
In fact, the latest available government statistics on the number of uninsured in America comes from the Census Bureau’s “Income, Poverty, and Health Insurance Coverage in the United States: 2007,” which is published every August. (The Census Bureau report that will estimate the number of uninsured in 2008 will be released later this month.)
The current report says that there were 35.920 million uninsured U.S. citizens and 9.737 million uninsured foreign nationals in the United States.
Table 6 on page 22 of the report says that in 2007 there were a total of 45.657 million uninsured people residing in the United States. The table provides a breakout on the demographics of these 45.657 uninsured, indicating that it includes 33.269 million native born citizens and 2.651 million naturalized citizens, for a total of 35.920 U.S. citizens who are uninsured.
The report also states there were also 9.737 million persons in the United States in 2007 who were “not a citizen” and who did not have health insurance.
The Census Bureau does not ask people their legal status, so the report does not indicate how many of these 9.737 million uninsured foreign nationals were illegal aliens, or legal permanent residents, or people studying or working in the United States.