In a two-page letter sent to the Citizens Union Monday, Education Secretary Arne Duncan offered a stern warning that placing restrictions on mayoral control could “turn back the clock and halt progress” and have “profoundly negative consequences for New York City’s students.”

We reported yesterday that Duncan had sent such a letter, but at the time U.S. Department of Education officials wouldn’t confirm that the letter existed. That changed a few minutes ago when an official e-mailed it over.

The full text of the letter is after the jump.