(NewsNation) — Independent presidential candidate Robert F. Kennedy Jr. canceled a planned appearance during an Iowa State Fair event Thursday, with his campaign citing “increased security concerns,” the Des Moines Register reported.

Kennedy was supposed to speak at 2:15 p.m. at the Des Moines Register’s Political Soapbox. His campaign said in a statement to NewsNation that they canceled Kennedy’s speech as they were “unable to secure a venue stage indoors to satisfy our security requirements.”

According to the newspaper, there were 10 people including Kennedy scheduled to speak at the Soapbox, an event that has attracted politicians from across the nation, and become a state tradition.

“I believe the campaign wanted Mr. Kennedy to speak at the Des Moines Register Political Soapbox and worked hard to make that happen, and the Iowa State Fair has always worked diligently to accommodate all candidates’ needs,” Register Executive Editor Carol Hunter said. “But the campaign’s understandable security concerns in the end couldn’t be satisfactorily addressed.”

Hunter said she was not told of specific threats, though the campaign had general concerns about the busy fairgrounds’ open-air stage.

In July, President Joe Biden directed Homeland Security to give Kennedy Secret Service protection after a gunman attempted to assassinate Republican presidential nominee Donald Trump at a rally in Pennsylvania.

A source familiar with RFK Jr.’s security operations told USA TODAY, “I’m not tracking any type of conversations like that, certainly not to the level that we had with Trump.”