Former Baltimore city schools chief Andres Alonso is in the running to become Newark’s next school superintendent, according to the head of the Newark Teachers Union — which Alonso appeared to confirm in a cryptic tweet.

Alonso, a Harvard University education professor who was a top official in New York City before running the Baltimore school system for six years, was reportedly a candidate to become Los Angeles’ next superintendent. But he withdrew his name on Monday, he said in a tweet.

He made the decision after “a possibility emerged – no guarantee – in relation to the school system I first loved,” he wrote on Twitter late Thursday.

Alonso did not say which system he was referring to, but he spent the first 12 years of his career teaching special education in Newark. (He later tweeted that the school system in question is not Baltimore.) On Friday, he declined to comment whether he is vying for the Newark superintendent position, which the school board is expected to fill by the end of May.

But Newark Teachers Union President John Abeigon told Chalkbeat that a source with knowledge of Newark’s superintendent search informed him that Alonso was a candidate. That prospect has alarmed Abeigon, who wants the district to choose someone with no ties to the district’s most recent leaders.

In a Facebook post on Wednesday, Abeigon wrote that it was “frightening” that the search committee would consider Alonso, whom Abeigon said is “cut from the same cloth as Cami Anderson/Chris Cerf” — the district’s previous two state-appointed superintendents whose often-controversial policies the union bitterly opposed. Anderson oversaw the closure of many district schools and expansion of charter schools, along with sweeping changes to the teachers contract that included merit-based pay and an overhauled evaluation system.

Abeigon added in his post that the committee should be able to find a “certificated homegrown educator” — “Preferably one not associated with the reform ilk that has left us in shambles.”

In Baltimore, Alonso cut the size of the department’s central office and reorganized resources to give principals more power over how to use school budgets. He also negotiated a teacher pay system that eliminated seniority steps and, for the first time, tied compensation to performance. Alonso closed more than two dozen schools due to low performance and doubled the size of the charter school sector, from 17 to 34 schools. Graduation and attendance rates spiked and suspension rates fell.

He did all of this without making any real enemies before resigning on good terms in 2013 — a rarity for an urban superintendent. And union leaders he’s worked with have endorsed him in the past: American Federation of Teachers chief Randi Weingarten has said his management style was one reason Baltimore’s teacher evaluation system worked when evaluations proved divisive in so many other cities.

The only candidate so far to publicly acknowledge that he is in the running to become Newark’s next superintendent is Robert Gregory, the district’s interim superintendent who spent more than 20 years as a Newark teacher and principal before becoming an assistant superintendent under Cerf. While several board members have expressed a preference for a Newark-based candidate, a state-created plan to guide the district back to local control stipulated that the committee had to conduct a national search.

Alonso’s decision to withdraw his application for the Los Angeles job on Monday would align with the timing of Newark’s search.

The search committee — which consists of three board members and four individuals appointed by the mayor state education commissioner — recently concluded its candidate interviews and chose a few finalists, according to board and search-committee member Leah Owens. The full board will learn who the finalists are this weekend, before voting on their choice to be superintendent next month.

The finalists will be announced publicly after the board is informed, Owens added. But for now, “we’re still confidential.”

Philissa Cramer contributed reporting.

Correction: An earlier version of this story incorrectly stated that the Baltimore school district is seeking a new CEO.