Of the 46 million "without insurance", many millions are illegal aliens, many more could afford coverage but choose not to (e.g., singles in their 20s), and many more are between employment and coverage (i.e, temporarily have no coverage). When all is said and done, the actual number "without insurance" is closer to 25 million. Nothing like overstating the number by better than 80% to make the point.
BTW, no one is denied medical treatment at an emergency room -- not the uninsured, not illegal aliens, no one. In essence, then, everyone has health care insurance.