Ohio Gov. John Kasich will address the annual NAACP convention in Cincinnati on Sunday, a day before the Republican National Convention kicks off in Cleveland.

Kasich was the last GOP primary challenger to presumed presidential nominee Donald Trump, and has not endorsed Donald Trump.

Earlier this week, Trump declined an invitation to address the NAACP convention because of its conflict with the RNC. Hillary Clinton will speak to the NAACP on Monday.

"[O]ur convention really will be an opportunity for anyone running for president to provide a window into not only their policies, but into their heart and character as a candidate," NAACP President and CEO Cornell William Brooks told CNN on Tuesday.

Kasich is set to return to Cleveland after his early-evening remarks in Cincinnati. However, he is not yet slated to speak at the RNC.

The NAACP is the oldest African-American civil rights organization in the U.S.