One of the first things that’s likely to happen if the state Senate allows mayoral control to expire tomorrow is a vote on whether to retain chancellor Joel Klein.

Four of the five borough presidents, who will make that decision, have already committed to keeping the chancellor in power.

Letting mayoral control expire would revert the school system to its pre-2002 structure, which is run by a seven-member Board of Education. The borough presidents would appoint five of these members and the mayor would name the other two. It would fall to these appointees to select a schools chancellor, and there’s little doubt they would name Klein.

The lone hold-out is Bronx Borough President Ruben Diaz, Jr. “He has mixed opinions on the chancellor,” said John DeSio, a spokesman for Diaz.

Asked if Diaz would instruct his appointee to vote in favor of Klein, DeSio would not comment.

All of the other borough presidents, or their school board appointees, have said they would favor retaining Klein as chancellor.

At a press conference last week, Manhattan Borough President Scott Stringer said step two after reconfiguring the board would be to “schedule an immediate vote on the retention of Joel Klein.”

In a piece on Huffington Post, he wrote, “For the sake of stability, I favor keeping Chancellor Klein in his position and preserving the Chancellor’s existing authority.”

Stringer and Patrick Sullivan, his appointee to the current citywide school board, the Panel for Education Policy, have never given Klein rave reviews.

Sullivan is the PEP’s fiercest critic of Klein’s policies and is the sole panel member to regularly vote against the Department of Education’s proposals.

For his part, Stringer has called for the local school boards, known as Community Education Councils, to become independent from the DOE. This change would make them similar to the city’s community boards.

In the spring of last year, he released a report criticizing the Department of Education for not building enough schools to meet the growing demand in Manhattan.

Yet, Sullivan can’t imagine the Board of Education firing Klein. “I can’t see that,” he said. “I think it’d be highly unlikely.”

“If a new board must be appointed, I believe they should vote to retain Joel Klein in his current position,” Brooklyn Borough President Marty Markowitz wrote in a statement last week. “Mayoral control and the leadership of Chancellor Joel Klein have been good for New York City schools and our children.”

Dmytro Fedkowskyj, who was appointed to the PEP by Queens Borough President Helen Marshall, said he would like to see fixed terms for the PEP. Still, if he were appointed to the Board of Education, he would support Joel Klein. “As far as changing a horse in midstream, that could be catastrophic,” he said.

James Molinaro, the Staten Island borough president who fired his PEP appointee in 2004 when the person disagreed with a Bloomberg administrations policy, is also supporting Klein.