Bronx Borough President Ruben Diaz Jr. is putting his support behind one of his peers.

Diaz Jr. is endorsing Brooklyn Borough President Eric Adams in the Democratic primary race for mayor. 

Diaz Jr., once considered a formidable candidate himself, announced he would not seek the nomination in January 2020. He is expected to formally make the announcement endorsing Adams on Monday, the Adams campaign confirmed. 

The endorsement could serve as a significant boost for Adams among the city's Latino electorate -- a voting bloc which Diaz Jr. had been expected to capture given his long time in politics serving in the state assembly and as borough president in the Bronx. 

"Bronx BP Ruben Diaz Jr. is the city's strongest, most effective leader on behalf of the Bronx & Latino New Yorkers and I'm honored to have his support," Adams wrote on Twitter. "Ruben and I are from different boroughs but we come from the same place and together, we'll fight to make this city fairer for all," he added.

Latino voters could play a major role in the upcoming primary, and Diaz Jr.'s support could prove pivotal in the Bronx since no other candidates live or have represented the borough before. 

Support from prominent Latino leaders has been spread out throughout the Democratic mayoral field.

In recent weeks, Adams has sought to shore up support from the Latino community. Earlier this month, Fernando Ferrer, the former Bronx Borough President and twice mayoral candidate endorsed his campaign. 

Dianne Morales, a former nonprofit executive, is the only Latina in the race. She was born to Puerto Rican parents and lives in Brooklyn. On the Republican side there is Fernando Mateo, who is originally from the Dominican Republic and has previously advocated on behalf of livery cab drivers and bodega owners.