Republican presidential candidate Donald Trump speaks during a campaign rally at the Million Air Orlando, which is at Orlando Sanford International Airport on October 25, 2016 in Sanford, Florida.

Republican nominee Donald Trump has a message for voters, but it likely is not going to be effective enough to clinch the presidency or siphon many early voters away from Hillary Clinton, one election expert said.

"This is a good time to make an important public service announcement because a lot of things have happened over the last few days," Trump said at a rally earlier this week. "This is a message for any Democratic voter who have already cast their ballots for Hillary Clinton and who are having a bad case of buyer's remorse — in other words, you want to change your vote."