Tucson Mayor Regina Romero reminded President Trump of his outstanding debt to the city in a letter Friday afternoon, saying the president’s campaign still owes Tucson taxpayers $80,000 from a rally that was held at the Tucson Convention Center in 2016.

Trump is scheduled to hold a rally in Tucson again on Monday, which Romero said could cost the city an additional $50,000.

“Ensuring the security of this event and of the President of the United States is our utmost priority and we are happy to provide any support you may need during your visit,” Romero wrote. “Based on our current understanding of your campaign event on Monday, the City’s cost estimate for public safety response services is $50,000. Since this is a campaign event, we respectfully request that you reimburse the city and its taxpayers for these expenses.”

Tucson isn’t the only city that is waiting for the president to return taxpayer dollars, according to a report published by the Center for Public Integrity in April.