Seema Verma, who heads the Centers for Medicare and Medicaid Services, wrote on Twitter on Wednesday: "The scariest Halloween costume of the year is coming on …"
The tweet then showed a picture of a person wearing a T-shirt bears the inscription "MEDICARE FOR ALL" on the front.
"Medicare-for-all" is a proposal designed to extend Medicare, which covers the elderly and some people with disabilities, to all Americans to reduce the uninsured rate.
Politics, however, has been widely criticized by Republicans – including President Donald Trump.
"In practice, the so-called Medicare would do for all the Democratic Party. Be really Medicare for None," Trump wrote in the editorial. "According to the Democratic plan, today's Medicare would be forced to die."
"That would guarantee everyone could get the health care he needed without having to go to much less cost than the current dysfunctional system," he wrote.
"The reason why people are calling for" Medicare-for-All "is not because the ACA worked to eliminate the problems of our system, but because it is not," Verma said in her prepared remarks at a conference on Medicare. referring to the Affordable Care Act, which in 2010 was known under the name Obamacare Health Law.
"But their solution is, literally, doing more of what's not working, it's like the man who has a headache, who then takes a hammer on his head to make it disappear," she said.
 CNN's Tami Luhby, Greg Krieg, Eli Watkins and Katie Lobosco have contributed to this report.