As part of his campaign rollout in late February, Vermont senator Bernie Sanders appointed four national co-chairs to helm his bid for the presidency. While the selection of Ohio state senator Nina Turner, California representative Ro Khanna, and Ben and Jerry’s co-founder Ben Cohen surprised few, Sanders’s fourth choice was atypical.

Carmen Yulín Cruz is, by all traditional measures, an odd choice. The current mayor of Puerto Rico’s capital city, San Juan, she has neither fundraising acumen nor a substantial electoral base that will play a major role in the Democratic primaries. Never before has a Puerto Rican officeholder been given such a prominent position in an American presidential campaign. Not once has a presidential contender so explicitly embraced a Puerto Rican politician on the left-wing of one of the island’s two major political parties.

When she came to prominence in the aftermath of Hurricane María, Cruz was at the beginning of her second term as mayor of San Juan. She had first stepped into this role in 2012, in one of the most surprising recent upsets in Puerto Rican politics.