Retired pediatric neurosurgeon Ben Carson is expected to jump into the Republican primary race on May 4.
Caron said Monday he will make a major announcement at an event in Detroit that day.
Carson is considered a Washington outsider because he has never run for office. He became nationally known in 2013 when, as a pediatric neurosurgeon, he criticized the Affordable Care Act, comparing it to slavery and Nazism.
Although Carson is widely expected to announce his candidacy, spokeswoman Deana Bass said she was not ready to confirm that.
"He will make an announcement. But he's still very much in the exploratory phase, so he hasn't made a decision yet," Bass told CNN.
NBC reported Monday that Carson definitely plans to start his presidential campaign at the May 4 event in his hometown.
Carson has been traveling across the country for the past six months, giving paid speeches and gauging interest in a possible candidacy.
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A recent poll by Real Clear Politics ranks Carson in the middle of 12 possible Republican candidates, ahead of Marco Rubio, who announced his candidacy on Monday.
An NBC News/Wall Street Journal poll found more than 40 percent of GOP voters could imagine supporting Carson.
A political action committee backing Carson, who would be the only African-American candidate for the Republicans, raised more than $13 million in donations in 2014. A presidential exploratory committee formed last month reportedly brought in more than $2.1 million in its first 28 days, according to a statement by Barry Bennett, the campaign's manager.
So far, Sen. Marco Rubio of Florida, Sen. Rand Paul of Kentucky, and Sen. Ted Cruz have entered the race for the GOP presidential nomination.
