Ben Carson, the newly confirmed secretary of housing and urban development (HUD), referred to slaves as "immigrants" during a speech Monday.
Carson was speaking to HUD employees in Washington, DC, when he said, "There were other immigrants who came here in the bottom of slave ships, worked even longer, even harder for less.
"But they too had a dream that one day their sons, daughters, grandsons, granddaughters, great-grandsons, great-granddaughters, might pursue prosperity and happiness in this land," Carson added.
Carson, a retired neurosurgeon who sought the Republican presidential nomination before throwing his support behind President Trump, was confirmed as housing and urban development secretary last week.
Carson's comments about slavery quickly prompted criticism, including a tweet from the NAACP.
By Monday afternoon, Carson was a top trending topic on Twitter in the US, with many expressing incredulity and anger over his remark.
Later Monday, Carson tweeted that "you can be an involuntary immigrant," and said that an immigrant is "a person who comes to live permanently in a foreign country."
However, he appeared to walk that sentiment back hours later when he posted a statement to Facebook saying the "the slave narrative and immigrant narrative are two entirely different experiences."
"Slaves were ripped from their families and their homes and forced against their will after being sold into slavery by slave traders," Carson said in the statement. "The Immigrants made the choice to come to America."
He went on to say that "the two experiences should never be intertwined, nor forgotten."
The Department of Housing and Urban Development did not comment on the controversy Monday.