Retired physician Ben Carson, considered a potential Republican presidential contender, plans a major announcement on May 4 in Detroit, CNN reported on Monday, citing his spokeswoman.
"He will make an announcement. But he's still very much in the exploratory phase, so he hasn't made a decision yet," the spokeswoman, Deana Bass, told the network.
Carson, 63, who is popular with Tea Party conservatives, said in February he was considering a possible presidential announcement in May.
He would be the first African-American to enter the growing Republican field of candidates for the party's presidential nomination next year.
Florida Senator Marco Rubio announced his candidacy on Monday, joining fellow Senators Ted Cruz and Rand Paul.
Among other possible Republican contenders are former Florida Governor Jeb Bush and Wisconsin Governor Scott Walker.
(Reporting by Peter Cooney; Editing by Paul Tait)