Reps. Joaquín Castro (D-Texas) and Raúl Grijalva (D-Ariz.) endorsed former New York City Council Speaker Melissa Mark-Viverito in a contentious primary in one of the Empire State's most Democratic congressional districts.

Mark-Viverito is running against 11 other Democrats to replace retiring Rep. José Serrano (D-N.Y.), who's been in Congress since 1990. The winner of the primary on June 23 is likely to be elected in November in the safe blue district.

The endorsement is unusual since Castro, chairman of the Congressional Hispanic Caucus (CHC) is endorsing Mark-Viverito, even as the CHC's campaign arm, Bold PAC, is endorsing New York City Council member Ritchie Torres.

Mark-Viverito, a prominent activist and politician, also briefly led Latino Victory, a major Hispanic progressive political advocacy organization, and unsuccessfully ran to be the New York City public advocate in 2018.

“Melissa Mark-Viverito is exactly the type of Latina powerhouse that we need in Congress. Today I am proud to announce that I am endorsing her candidacy for NY-15 in the Bronx,” said Castro in a statement.

“The last few months have made one thing very clear: the only way that we are going to see the change we need in our country is by electing someone whose values are unwavering, who has the experience to get things done, and who has a pulse on the needs of the people; someone like Melissa Mark-Viverito," he added.

The endorsement from two of the most prominent members of the CHC comes at a key time for Mark-Viverito, who is competing against a better funded candidate in Torres.

Also running is Rev. Rubén Díaz, Sr., a pentecostal minister with controversial anti-LGBTQ views who has launched an unorthodox grassroots campaign. Rubén Díaz is the father of Rubén Díaz Jr., the Bronx borough president, who has not endorsed his parent.

"I've fought alongside Melissa Mark-Viverito for years. She has the commitment, experience and energy to work with me in Congress for the benefit of the Bronx and all Americans," said Grijalva.

"When you need a fighter for a tough battle, you want Melissa in your corner. Melissa and I were arrested together in front of Trump Tower demanding justice for immigrants. She is the type of colleague I need to finally end family separation and create a path to citizenship for our hard-working, tax-paying undocumented families who remain in the shadows," added Grijalva, the chairman of the House Natural Resources Committee, which among other issues has oversight of federal legislation on Puerto Rico.

Puerto Rico-born Mark Viverito has been a vocal advocate on immigration issues and on supporting Puerto Rico – positions close to those voiced by Castro and Grijalva in Congress.

“I could not be prouder to secure the endorsement of two leading voices in Congress for the Latino community – Congress member Joaquin Castro and Raul Grijalva,” said Mark-Viverito.

“As the first Puerto Rican and Latina to serve as Speaker of the New York City Council, I know just how much it means for Latinos to have a voice in government," she added.

New York's 15th Congressional district is among the most Democratic in the country – President Trump received less than 5 percent of the district's vote in 2016 – and one of the most heavily Hispanic districts, with 65 percent of the population identifying as Hispanic or Latino, according to the U.S. Census.