"Who you are, what you are, does not change after you occupy the Oval Office. All it does is magnify who you are. All it does is shed a spotlight on who you are," Obama said.
The president listed off a number of Trump's most controversial statements, like threatening to throw Hillary Clinton in jail and how he has used his celebrity to make unwanted advances on women.
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"You will have more power to carry out the twisted notions you had before you were in office. So you can't make excuses for this stuff. This isn't a joke," Obama said.
The president has lamented the "reality TV-ized" atmosphere of the campaign, telling supporters the election is not "Survivor" or "The Bachelorette."
"Looking at Air Force One @ MIA. Why is he campaigning instead of creating jobs & fixing Obamacare? Get back to work for the American people!" Trump tweeted.
Polling shows the Sunshine State is a tossup just five days before the election. An NBC News/Wall Street Journal/Marist poll released Sunday shows Clinton earning 45 percent support and Trump with 44 percent.