Baltimore’s Democratic mayor will take an indefinite leave from office after it emerged she secured a lucrative sales deal with the University of Maryland Medical System for a kids book series she wrote — while she sat on its board.

Mayor Catherine Pugh announced Monday she will step away from the job as she faced intensifying backlash for netting more than $500,000 from the sale of the books, secured with a no-contract bid arrangement with the institution.

While a UMMS board member, Pugh cashed checks from book sales as part of a deal made in 2011 with the medical system to distribute her self-published “Healthy Holly” illustrated series to Baltimore schoolchildren, according to news station WBAL-TV.

The Democrat — who became mayor in 2016 — called the deal a regrettable mistake last week in a news conference. She recently returned $100,000 to the medical system and resigned from the board, which she served on for nearly two decades, her office said.

Pugh abruptly announced her leave of absence as mayor as the mushrooming scandal threatened to upend her political career. The decision came the same day Maryland’s governor called for the state prosecutor to investigate the corruption allegations.

Gov. Larry Hogan slammed the mayor, calling the arrangement “deeply disturbing” and urging her to resign immediately.

“I am particularly concerned about the UMMS sale because it has significant continuing ties with the State and receives very substantial public funding,” the Republican governor wrote in the letter obtained by news station WBAL-TV.

The mayor’s office, however, insisted her leave was unrelated to the scandal. Pugh, 69, can no longer serve the city due to a bout of pneumonia, they claimed.

“She’s been advised by her physicians that she needs to take time to recover,” her office’s statement said, which added “with the Mayor’s health deteriorating, she feels as though she is unable to fulfill her obligations as Mayor of Baltimore City.”