When President Barack Obama pitched the Affordable Care Act to Congress, he assured lawmakers the landmark legislation would exclude millions of people in the country illegally.
"You lie!" hollered Republican Rep. Joe Wilson of South Carolina, a rejoinder that not only shredded protocol but underlined the emotionalism surrounding the issue.
(Wilson was not only rude but factually off base when he interrupted Obama's 2009 speech and assailed the president.)
Politics aside, advocates say there are practical reasons to extend health care coverage to every American, regardless of immigration status.
Hospitals are obliged by federal law to offer emergency treatment to anyone who comes through the door, whatever their immigration status or ability to pay. Historically, that has placed a substantial burden on many urban providers of last resort, such as L.A. County-USC Medical Center.
"We already pay for the health care of undocumented immigrants," Julian Castro, one of the Democratic presidential hopefuls, noted on ABC. "It's called the emergency room."
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Beyond that fiscal reality, there are public safety considerations.
Many physicians, hospital officials and public health leaders say it makes little sense to deny coverage to undocumented immigrants, warning, for example, that infectious diseases may spread more quickly if people are discouraged from seeking medical care.
Yet even as Democrats push for greater access to coverage -- through "Medicare for all" or marketplaces created under the Affordable Care Act -- Trump has moved in the opposite direction.
Recently, the administration unveiled its so-called "public charge" regulation, which could deny green cards -- a step toward citizenship -- to immigrants who receive certain forms of government assistance, such as Medicaid.