Florida voters who receive the call, audio of which was obtained by NBC News, hear a man speaking in a minstral dialect who identifies himself as Gillum, the mayor of Tallahassee who won his party's primary Tuesday.
Over a soundtrack of drums and jungle noises, the man says, "We Negroes...done made mud huts while white folk waste a bunch of time making their home out of wood an stone." The impersonator says the huts would useful housing in a hurricane. He also says he'll pass a law letting black people escape arrest "if the Negro know fo' sho he didn't do nothin.'"
Voters reported receiving it Friday, according to the Tallahassee Democrat, which first reported the call.
A disclaimer at the end of the recording says it was paid for by The Road to Power, a white supremacist and anti-Semitic group based in Idaho that has made other offensive robocalls, including one in Charlottesville, Virginia, after a far-right rally there last year, and another identified Friday in Iowa.
A spokesperson for Gillum's Republican opponent, Rep. Ron DeSantis, condemned the robocall as "absolutely appalling and disgusting" and said he hoped "whoever is behind this has to answer for this despicable action."
"Our campaign has and will continue to focus solely on the issues that Floridians care about and uniting our state as we continue to build on our success,” DeSantis spokesperson Stephen Lawson added.
Republican Gov. Rick Scott, who is running for Senate, also condemned the message.
The governors race become radicalized almost immediately this week when DeSantis urged Floridians not to "monkey this up" by electing the Gillum. Democrats and others called the word choice a racial dog whistle, while Gillum said it wasn't a whistle but a "bullhorn."
DeSantis' campaign also acknowledged Thursday that he had been an administrator of a Tea Party Facebook group that included racist content, but said the candidate was completely unaware and deleted his connection to the group as soon as he found out about it.
Separately in Iowa, authorities there confirmed that robocalls citing the slaying of an Iowa college student are from the same white supremacist group, but there's apparently little the officials can do.
Lynn Hicks, a spokesman for the Iowa attorney general's office, said Friday that prosecutors have no authority because there's no apparent effort to deceive anyone for commercial purposes. He called it a “tricky First Amendment issue.”
It’' unclear how many of the robocalls have been made since they began Tuesday, two days after Mollie Tibbetts’ funeral in Brooklyn, Iowa. They reference comments her father made in defense of Hispanics when he addressed friends and family.
A man officials suspected of being in this country illegally is charged with her murder. The calls describe him as "an invader from Mexico."
Various members of the Tibbetts family have spoken out against those on the right who have used the killing as a reason to propagate anti-immigrant rhetoric.
Associated Press attempts to reach The Road to Power were unsuccessful.