The Bloomberg administration is beginning a drive to remove unsatisfactory teachers, hiring new teams of lawyers and consultants who will help principals build cases against tenured teachers who they believe are not up to the job. It is also urging principals to get rid of sub-par novices before they earn tenure.

At the center of the effort is a new Teacher Performance Unit of five lawyers, headed by a former prosecutor fresh from convicting a former private school principal who had a sexual relationship with a student.

A separate team of five consultants, including former principals, will work with principals to improve struggling teachers’ performance. In cases where the teachers fail to get better, the consultants will help amass the documentation necessary to oust them.

The plans, at a cost of $1 million a year, are described in a memo and an accompanying letter to principals from Schools Chancellor Joel I. Klein. In the letter, he urged principals to help teachers improve but added, “When action must be taken, the disciplinary system for tenured teachers is so time-consuming and burdensome that what is already a stressful task becomes so onerous that relatively few principals are willing to tackle it. As a result, in a typical year only about one-hundredth of 1 percent of tenured teachers are removed for ineffective performance.