Biden had two events scheduled in Iowa.
More than 19 million people have already voted in the presidential election, either by mail or in person. No votes will be counted until Nov. 6, but some key states are releasing the party affiliation of those who have voted.
Democrats have an edge in votes cast in Florida, Iowa, Nevada, North Carolina and Ohio. Republicans have an advantage in Colorado.
Associated Press writer Kasie Hunt in Jacksonville, Fla., contributed to this report.
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