Retired police commissioner William Gross declared on Thursday his support for Annissa Essaibi George in Boston’s mayoral race, solidifying her standing as a moderate in a field dominated by progressives.

“This is the person that I whole-heartedly believe can bring this city together, make it more cohesive,” Gross, 57, said at a news conference in Mattapan.

The city’s first Black police commissioner, who former mayor Marty Walsh appointed in 2018, had briefly considered running for mayor after he retired in January.

Gross said Essaibi George, an at-large city councilor who lives in Dorchester, easily earned his endorsement by familiarizing herself with the city’s diverse neighborhoods and being even-handed in her dealings with the police force.

“There is too much separation, not only in our great nation, but some people are trying to do that in the city of Boston. I’ve seen Annissa in every neighborhood before the mayoral race,” he said, implying that other unnamed candidates have been trying to capitalize on “anti-police sentiment” since the murder of George Floyd in Minneapolis nearly a year ago.

“As police commissioner, [she] definitely held me accountable and the officers, but she was fair about it,” Gross added, speaking in Mattapan Square.

“At least when she has a question, no offense to [the media], I would get a call,” he said. “Some people run straight to the media without allowing us to quantify or contextualize anything.”

Gross identified “fair and impartial policing, procedural justice, de-escalation,” as the main areas of police reform he’d like to see Essaibi George address if elected.

The announcement comes as the historically diverse field of mayoral candidates has begun staking out positions on the contentious issues of police reform and funding.

Essaibi George, who is Polish- and Arab-American, is the only candidate who has declared opposition to shifting some portion of the police budget to social services. She also stood out at a recent forum as the only candidate who does not support removing police, known as school resource officers, from the city’s public schools — a demand of local Black Lives Matters leaders.

Gross and Essaibi George announced the endorsement outside a popular deli as part of a campaign tour of businesses in Mattapan, where U.S.-born African Americans and Black immigrants from the Caribbean predominate.

“When I think about the work that is left undone here in the city of Boston … it’s about strengthening the relationship between the community and police, it’s about strengthening the bonds of trust between community and police and making sure as we work towards that that we are doing that together,” she said.

Responding to reporter’s questions about her racial-ethnic identity, Essaibi George, 47, said her heritage as the daughter of an Arab father and Polish mother “are very important and critical elements” to her identity.

Asked which box she checks when filling out a census form, Essaibi George said she did not to check any because there is no box for Arab Americans and those of Middle Eastern or North African descent. So she wrote it in.

“I think it’s absolutely ridiculous that I stand before you with a record of achievement, a record of great work on the Boston City Council … and talk about my identity,” she added. “We should be talking about the work.”

Rev. Miniard Culpepper, a political observer who is backing Acting Mayor Kim Janey in the race, discounted the influence of the Gross’ endorsement because the police department “has some soul-searching to do,” he told GBH News.

“If I were the commissioner, my endorsement would be a powerful one. I can’t say the same for Commissioner Gross,” said Culpepper, pastor of the Pleasant Hill Missionary Baptist Church near the Dorchester-Roxbury line.

“I have more of a connection to the people,” he said. “He’s got a connection to the police. I think those are two very different connections.”

Gross characterized the adversarial stance other candidates have taken against police as misguided.

“If you think you can get votes off of ‘us versus them,’ ‘we’re going to save you from police’ — you really need to get out and talk to people about crime, about how to end crime, by providing resources and how to bring the community together by investing in our future, which are the children,” he said.