The endorsement in the 13th District Race is a key pickup for Espaillat in the battle against Rangel, who has represented the area since he unseated Adam Clayton Powell Jr. in 1970. Espaillat lost a close race to Rangel for the seat in 2012.
"We believe that with Adriano Espaillat, we will continue to move forward not just for Manhattan but also for the borough of the Bronx," Diaz told those assembled a recent press conference.
The borough president, who endorsed Rangel in the last election, described Espaillat as a champion for economic development, affordable housing, education and immigration reform who could help bring northern Manhattan together with The Bronx, both of which are included in the district.
Diaz said he was also confident that Espaillat would help the borough with money for transportation and housing.
Espaillat has received the endorsement of Bronx Democratic County Committee Chairman and state Assemblyman Carl E. Heastie, who represents part of the north Bronx as well.
He said in a statement that he was "truly humbled to have the support of the Bronx County Democrats" and would make opening an office in the Bronx one of his first actions in Congress.
The 13th district includes Bronx communities such as Kingsbridge, Norwood and Fordham and Manhattan communities such as Washington Heights, Harlem and Morningside Heights.
In addition to Espaillat, the embattled Rangel is facing off against Bronx community activist Yolanda Garcia and senior pastor of Harlem's First Corinthian Baptist Church Michael Walrond.
The 22-term Rangel, who has been endorsed by Sen. Charles Schumer among others, emphasized the importance of keeping him in Congress based on his seniority and experience.
"From Norwood to Inwood to Harlem, there is strong, grassroots support for Congressman Rangel’s reelection from the voters of the 13th Congressional District," the congressman's campaign said in a statement. "We can’t afford to lose the experience and seniority Congressman Rangel brings to the table."