Prosecutors say 65-year-old Austin Winther, of Philadelphia, tried to lure a supposed Idaho woman and her 13-year-old daughter to travel to Pennsylvania for a sexual tryst. They say he also tried to send the daughter obscene images.
The mother and daughter were actually undercover police officers.
Federal prosecutors say Winther entered a plea Monday to an interstate sex charge and four obscenity counts. He faces six-and-a-half to eight years in prison under federal guidelines. He remains in custody pending his April 13 sentencing.
A defense lawyer did not immediately return a call for comment.
Winther taught at Rider's Graduate School of Education in Lawrenceville, N.J., from 2005 until late 2009.