Mrs. Obama aimed her appeal to middle-class supporters, recalling her father's job as a pump operator to remind them that she and the president understand the importance of rewarding hard work and giving everyone an equal opportunity.
"When it comes time to stand up for the middle class...who's going to have your back?" said Mrs. Obama. She spent nearly 20 minutes talking with volunteers in the crowd after her speech.
Rep. Debbie Wasserman Schultz, a congresswoman from South Florida and chair of the Democratic National Committee, also spoke at the event, warning seniors that Republican presidential nominee Mitt Romney and running mate Paul Ryan's budget "would end Medicare as we know it."
Kennedy reported from Fort Lauderdale. Associated Press writer Nancy Benac in Washington contributed to this report.
Follow Brendan Farrington on Twitter at https://twitter.com/bsfarrington
Follow Kelli Kennedy on Twitter at https://twitter.com/kkennedyAP
Copyright 2012 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.