By Gregory Wallace

WASHINGTON (CNN) -- An unusual security arrangement for Education Secretary Betsy DeVos is costing taxpayers upwards of $1 million per month.

Citing a determination that "a threat to the secretary's safety exists," the US Marshals Service said it would continue providing her a security detail, though it would not detail the nature of the threat.

The marshals began protecting DeVos days after protesters blocked a doorway and prevented her from entering a middle school near her office in Washington.

The agreement has the Education Department reimbursing the marshals $7.78 million this fiscal year, which works out to nearly $34,000 per day. It covers from February 13, when marshals began providing her security, and extends through September 30, the end of the government's fiscal year, Lynzey Donahue, a spokeswoman for the marshals, told CNN on Friday.

Security for tens of thousands of federal judges, prosecutors and other court employees is one of the marshals' key responsibilities. The service operates an around-the-clock national threat management center that handled 2,357 threats last year, according to the agency. Deputy marshals also apprehend fugitives, secure prisoners and run the federal government's witness protection program.

But it rarely handles protection for Cabinet officials. The marshals said it last did so when the Office of National Drug Control Policy's director held Cabinet rank, which ended in 2009.

The size of the protection team for DeVos is "commensurate with the existing threat and based on USMS protective service requirements, experience and methodology," Donahue said, but declined to provide further details.

At the same time, the US Secret Service has its hands full protecting President Donald Trump and his large, geographically diverse family. Homeland Security Secretary John Kelly said recently the service needs "a lot more agents" to handle the demands, especially after a busy election cycle that tapped the agency's resources. The Secret Service said it is supplementing its regular presidential protection team with special agents who normally work criminal investigations in regional offices around the country.