Former President Donald Trump’s campaign scrapped plans for an upcoming outdoor rally in Wisconsin after the Secret Service said it did not have the personnel needed to secure the site, multiple sources told CBS News.

The rally was set to take place outdoors at an airport on Saturday, but Trump will instead deliver remarks at a smaller indoor arena in Prairie du Chien, Wisconsin. 

The Secret Service said it was short-handed due to the ongoing annual meeting of the United Nations General Assembly in New York. The service is responsible for providing security for foreign dignitaries while they are in the U.S.

A senior Secret Service official briefed on the planning for the Wisconsin rally said the agency was “never configured to provide such an elevated level of protection for an increasing number of protected.” The official was granted anonymity because they were not authorized to speak to the media.

“Our personnel and equipment are being pushed to their limits to sustain the current operational tempo,” the official said. “This proposed Wisconsin event also took place during the United Nations General Assembly, where the Secret Service is responsible for the safety and security of over 140 world leaders amid a challenged global threat level.” 

The change in venue comes after the Secret Service ramped up protection of Trump following the July 13 shooting at one of his rallies in Pennsylvania. A second apparent assassination attempt at his golf course in Florida was disrupted by a Secret Service agent earlier this month.

Agency leaders have implored Congress to provide more funding and resources to help the service meet its security obligations, while lawmakers have severely criticized the agency for the security failures that preceded the shooting in Pennsylvania. Congress approved a spending package that included $231 million in new funding for the service this week.

In addition to protection for foreign leaders, the Secret Service is tasked with safeguarding President Biden and his family, as well as all former presidents, vice presidents, their families and presidential and vice presidential candidates. Currently, the Secret Service safeguards roughly three dozen individuals on a full time basis.

“Former President Donald Trump is receiving heightened levels of U.S. Secret Service protection and our top priority is mitigating risks to ensure his continued safety at all times,” said Anthony Guglielmi, a Secret Service spokesman. 

After the first assassination attempt in Pennsylvania, the Trump campaign scaled back the number of outdoor rallies it holds. These rallies often require more security coordination and planning, since they can accommodate more attendees than an indoor rally. The former president has held just a handful of outdoor rallies since the assassination attempt in Butler.