Early returns showing a significant lead for Sanders.
"Maybe he doesn't want to get rid of the problem," Trump said.
Trump is currently leading by 17 percent, with John Kasich in second place.
The number is expected to surpass the record set in 2008.
The group spent millions of dollars on attacking President Obama in 2012.
Sharpton is also speaking with Hillary Clinton the same day.
The Texas senator slammed his GOP rival for supporting "socialized medicine."
"I would have to have major philosophical alignment with whoever it was," he said.
"That has no place in politics today," Jane Sanders said.
Hillary Clinton herself is not attending the two Wednesday events.