Laying the groundwork for a possible mayoral run, Bronx Borough President Ruben Diaz Jr. plans to endorse Harlem Assemblyman Keith Wright to succeed Charles Rangel in Congress.
The announcement is expected Thursday outside the Bronx County Courthouse building where Diaz has his office.
Sources said Diaz is backing Wright in hopes of expanding his own political base for a potential city-wide run for mayor in 2017.
The sources said Diaz’s backing is sure to be remembered by Wright, who is also the Manhattan Democratic Party chairman.
Diaz’s support is a coup for the Harlem legislator as he seeks to grow beyond his African-American base in a congressional district with a large and growing Hispanic population.
Diaz is Puerto Rican and the congressional district includes El Barrio — East Harlem — which has a large concentration of Puerto Rican residents.
The district also includes heavily Dominican Washington Heights in northern Manhattan as well as portions of The Bronx.
Diaz’s endorsement is sure to raise eyebrows in city political circles.
Two years ago, the borough president lined up with state Sen. Adriano Espaillat, a fellow Hispanic who is running once again for Rangel’s seat.
Diaz has other influential friends in his corner.
Gov. Cuomo Wednesday night hosted a birthday fund-raiser for Diaz at the Upper East home of real estate developer Keith Rubenstein.
The Bronx Beep also has strengthened his ties with officials in the city’s charter-school movement, many of whom have ties to wealthy donors who could back a future citywide campaign.
Another congressional candidate trying to succeed Rangel, Adam Clayton Powell IV, the former East Harlem assemblyman and councilman, dismissed Diaz’s endorsement of Wright as inconsequential.
Asked if a political quid pro quo was involved, Powell said, “I’m not privy to those machinations.”