New York City Mayor Bill de Blasio is requesting $35 million in reimbursement from the federal government for the cost of NYPD protection around Trump Tower.

“This is truly unusual, for the first time we have had the NYPD providing such a crucial role in providing security for the President-elect,” de Blasio said during a press conference Monday morning, announcing he is sending a letter to President Obama to “formally initiate the reimbursement process” between November 8 through Trump’s inauguration on January 20.

“We are going to be continuing very aggressively in the course of the next few days with calls and meeting with members of the Obama administration and members of the Congress to nail down the reimbursements,” de Blasio added. “ This is the time now to really lean into nailing down the reimbursement.”

The letter to President Obama comes shortly after half-dozen Democratic lawmakers sent the Mayor and Governor Andrew Cuomo a letter stating they should refuse to provide protection for Trump and his family in Trump Tower due to the cost and the traffic jams it has caused, unless the president-elect finance the cost himself.

“Municipal or state resources should not be subsidizing the President-Elect’s decision to maintain multiple permanent residences,” the letter reads. “For all these reasons, we respectfully request that New York City and the state refuse to pay additional security costs associated with maintaining a second residence at Trump Tower, once the President-elect is inaugurated. Should the President-elect choose to maintain two permanent residences for his family, it is reasonable to request he reimburse the city and the state for all additional security expenses from his own significant personal financial resources.”

Trump Tower, the site where President-elect Donald Trump resides and also the headquarters where his presidential transition is taking place, requires a massive security operation due to the area being the most heavily-trafficked during the holiday season. According to NYPD Commissioner James O’Neill, 100 additional officers are detailed a day — 50 officer on day tour and 50 on night tour, to help with the protection and surveillance needed around Trump Tower.

The request cost of about $500,000 per day in protecting the president-elect and his family has become an extraordinary burden for the city to expense. During the post-election press conference last month, de Blasio stated the city would need help from the federal government to cover the security cost and the overtime for NYPD officers, adding the city can’t cover the cost with the federal government help.

“This is a very substantial undertaking that will take substantial resources,” de Blasio said. “We will begin the conversation with the federal government shortly on reimbursement for the NYPD for some of the costs that we are incurring, in particular the overtime costs.”

De Blasio also told reporters that he spoke to Treasury Secretary nominee Steven Mnuchin regarding security reimbursement costs once Trump takes office.

“We had a good conversation and he fully understood that there is a real important discussion to be had on how we deal with reimbursement issues going forward” de Blasio said. “I think the key individuals in the incoming administration, including the president-elect, understand what a huge commitment the NYPD is making and I have every reason to believe they will be sympathetic and do all they can do.”