"We will be continuing very aggressively in the next few days — calls and meetings with members of the Obama administration and Congress — to nail down the reimbursements for the time between November 8 and January 20," the mayor said. "That will be the responsibility of the current administration."
Providing 24/7 high-level security at the Trump Tower, in a very popular tourist area in the heart of Manhattan, is a strain on the police department. An additional 50 police officers work daytime shifts to protect the area around Trump's residence.
"This is a highly-trafficked, dense urban environment, and one that presents an unprecedented and unique target for potential terrorist activity," de Blasio wrote in a letter to Congress. "No other President in modern history has had his primary residence located in such a densely-populated neighborhood."
Protecting a President or President-elect is the job of the Secret Service, but local law enforcement is routinely tasked with providing assistance.
Every President has local law enforcement protection when they return home, but Trump's protection is very high, due primarily to the location of his residence.
It is not known whether the cost of his protection will decrease when he moves into the White House, as Melania Trump and their 10-year-old son Barron will remain in midtown Manhattan and the President-elect has stated that he will visit them frequently.