There’s a new entrant in Boston’s already crowded mayoral race — Jon Santiago, a Democratic state representative and emergency-room physician at Boston Medical Center, is joining the field of declared candidates.

In a campaign kickoff video released today, Santiago referenced his time in the Dominican Republic with the Peace Corps, his service in the U.S. Army Reserve and his ongoing work at BMC, saying the latter gives him special insight into the challenges facing the city.

“I’ve come to learn that my patients are a reflection of Boston,” Santiago said at one point. “Their stories speak to our greatest challenges: disparities in health and wealth, rising rents, struggling schools.”

“Like the ER, I don't only see challenges in Boston,” Santiago added. “I see hope and fear amidst this crisis.”

Santiago joined the Massachusetts Legislature in 2019 after ousting longtime incumbent Byron Rushing, a high-ranking member of House leadership and one of Boston’s iconic Black politicians, in the 2018 Democratic primary.

Santiago, who represent the 9th Suffolk District, been a high-profile figure throughout the COVID-19 pandemic. He's discussed his experience treating patients at BMC in dispatches posted to social media and evaluated the state’s response in interviews with Boston-area media.

Santiago’s family moved from Puerto Rico to Roxbury when he was a child. He attended the University of Texas at Austin and the Yale School of Medicine. He lives in the South End with his wife, Alexandra.

Boston has never had a mayor of color, but Santiago joins a long list of contenders who could change that. City councilors Michelle Wu, Andrea Campbell and Annissa Essabi George have all announced they are running. Boston City Council President Kim Janey — who will become acting mayor if, as expected, the Senate confirms current Mayor Marty Walsh as President Joe Biden’s labor secretary — is also mulling a run.