John Hailer, a former executive at French bank Natixis, is OUT as interim head of the Boston Public Library.

The appointment of the well-connected banker, who has no library experience, to an influential job came under criticism from library supporters who said he was not qualified for the role and thought his background represented a lack of trust in Boston’s public institutions after last year’s marathon bombings.

According to a memo from interim library system leader Maurice Cox, Hailer of Natixis abruptly left the post on Wednesday night, just days into his three-month contract. “John Hailer was not interested in being a candidate for the permanent executive director position, which is understandable, and his decision to leave on his own is entirely his,” Cox wrote. “I wish him the best of luck with his future endeavors.” He did not immediately respond to a request for comment Thursday night.

John’s departure was announced on the same day that Mayor Martin J. Walsh rejected a list of three finalists for the permanent director’s job, which had been offered to him by the library’s board last week.

Walsh said he would instead seek recommendations for an executive director from the Boston Public Library’s leadership team, saying he believed it was “important that [the library] continue with an interim director until we can conclude a full search process and identify a permanent leader.” Walsh said he had asked to meet with the library board Thursday to discuss candidates, but they refused his invitation.

Library board chairman Paul S. Grogan, who led the search for a permanent director and hired John Hailer, said Wednesday evening he had not been informed by the mayor’s office that Walsh was declining to proceed with the candidates. “I don’t know why they would have rejected them,” he said. “But I will tell you this: if they reject them, they will have rejected a powerful list of candidates. And if they reject it because of something personal against Maurice or me, then it will be difficult for me to continue being on the board.”