The Republican first-term senator headlined a rally Friday afternoon at Arizona State University in Tempe.
Paul faces a crowded Republican primary race that includes former Florida Gov. Jeb Bush and Sen. Marco Rubio.
He will also be joined by Kelli Ward, an Arizona state senator aiming to run against longtime Sen. John McCain.
McCain, who has spent nearly three decades in the Senate, announced last month that he would be seeking re-election.
The Republican Party of Maricopa County is hosting the event.
An estimated 400-500 people attended the event. Most of them Rand Paul supporters.
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