After filing campaign papers with the city clerk Friday morning, Connecticut State Rep. Gary Holder-Winfield made official his bid for the mayor’s office.

Holder-Winfield is now the third candidate in the race, joined by Ward 10 Alderman Justin Elicker FES ’10 SOM ’10 and Sundiata Keitazulu, a plumber and New Haven resident. With Mayor John DeStefano Jr.’s announcement that he will not seek re-election after a record 10 terms in office, a number of other prominent New Haven residents and city officials are considering a run.

School reform has emerged as a defining issue in the campaign. In addition to a new face in the mayor’s office, a changeover will also occur this June in the school superintendent’s office. Superintendent Reginald Mayo is expected to retire when his contract expires on June 30, City Clerk Ron Smith told the News this week.

Assistant Superintendent Garth Harries, who has overseen much of the district’s school change process, will likely replace Mayo, Holder-Winfield told the News Tuesday. But Holder-Winfield has stressed the need for a re-evaluation of the way Board of Education members are appointed, a consideration that will likely play a role in the city’s charter reform process.

“Either way, Garth’s appointment shouldn’t be a done deal,” Holder-Winfield said. “We need to look at better ways of filling these spots so that the search process finds the best people possible.”

Beyond school board reform, Holder-Winfield said he will make early childhood education a centerpiece of his education reform platform, focusing on early intervention for students not meeting standards.

Other possible mayoral candidates — all of whom have suggested they might be interested in a run — include Hillhouse High School Principal Kermit Carolina, Probate Court Judge Jack Keyes, State Senate Majority Leader Martin Looney, Board of Alderman President Jorge Perez and State Rep. Patricia Dillon.