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Mayor Carmen Yulín Cruz of San Juan, an adversary of President Donald Trump, has signed on to be one of four national co-chairs of Sen. Bernie Sanders’ 2020 presidential campaign.

Her commitment to Sanders, the Vermont independent who announced his presidential bid on Tuesday, comes as the Democratic field is growing and competition for high-profile supporters is intensifying.

Cruz told NBC News in a telephone interview Thursday that she has working relationships with several of the senators who are running or may run. But she has been working with Sanders since 2016, “looking for a path for Puerto Rico.”

“A lot of the things he’s been fighting for all his life I’ve been fighting for all my life,” Cruz said. “Things like let’s not put wealth before health.”

She also named Sanders' efforts on education, collective bargaining, the rights of people in the LGBTQ and transgender communities, and other issues.

She said he has had a long commitment to being in the forefront of structural changes, even when they were not popular.

“Right now the United States has a president in the White House who is not up to the job,” Cruz said. “He does not represent values of integrity and unity, values of inclusion.”

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With Sen. Elizabeth Warren of Massachusetts, another Democratic presidential candidate, Sanders co-sponsored legislation to wipe out the island’s $73 billion debt that it still grapples with today.

Sanders also introduced a $146 billion Puerto Rico recovery plan. Neither bill made it out of committee.

Nonetheless, Cruz said in a statement that Sanders would offer “a new path toward the resolution of many of the issues facing Puerto Rico,” including a “new relationship" with the United States.

“In our darkest hour, he was there for us, not because it was politically convenient but because it was the right thing to do,” Cruz stated.

Cruz vaulted to national attention when she criticized the Trump administration's slow response to the 2017 hurricane.

Puerto Ricans on the island cannot vote in the general election, despite being U.S. citizens, but are able to vote in the primaries. Island residents who move to the mainland can vote in primaries and general elections once they register to vote in their state.

“This is personal. The president came and threw paper towels at us," Cruz said. "He continues to disregard the pain of people from Puerto Rico."

Sanders' support from Cruz, a high-profile Latina, could help him with minority communities.

Sanders struggled in his 2016 campaign to win black voters. Latinos divided generationally in the 2016 primary, with younger Latinos backing Sanders.

Along with Cruz, Sanders also named Ohio state Sen. Nina Turner; U.S. Rep. Ro Khanna, D-Calif.; and Ben & Jerry’s co-founder Ben Cohen as national co-chairs.

Cruz said not to expect to see her talking only to Latino groups and Turner only to African-Americans. There won’t be any “walls that keep us in our corner because that will be ineffective,” she said.

Cruz said she had conversations with other campaigns. Former Housing and Urban Development Secretary Julián Castro made Puerto Rico his first stop after announcing his presidential bid. Cruz walked him through a neighborhood, La Playita, still recovering from the hurricane and showed him initiatives taken to help residents prepare for the next storm.

“I think he, Julián, went into this for the right reasons,” Cruz said. “But again, I have a long-standing relationship with the senator and Bernie has a long-standing relationship with causes that touch the Latino community.”

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