South End state Rep. Jon Santiago ended his run for mayor on Tuesday, leaving five major candidates to compete for the top job inside Boston City Hall.

Santiago, who first launched his campaign in February, indicated he will be backing a woman of color.

An emergency room physician at Boston Medical Center in addition to his job at the State House, Santiago also serves as a captain in the US Army Reserve.

The field of candidates now includes Acting Mayor Kim Janey, Councillors At-Large Annissa Essaibi George and Michelle Wu, District 4 Councillor Andrea Campbell, and John Barros, former Mayor Marty Walsh’s economic development chief.

“It’s been an honor to join this historic field of candidates,” Santiago said in a video posted Tuesday morning. “I’m deeply proud of the race I’ve run, the relationships made and the impact our campaign has had.”

In what was likely a nod to polling that showed him in single digits, even after an ad campaign, Santiago added, “But the people of Boston have made it clear, and I look forward to supporting the first elected woman of color to lead Boston.”

The statement makes clear that Barros won’t be getting an endorsement. Santiago said he would be “in touch soon” about what’s next for him.

He is in his second term as a state representative for the district that includes the South End, Roxbury, Back Bay and Fenway. Fellow Beacon Hill Democrats had lined up behind his candidacy, including House Speaker Ron Mariano of Quincy.

If he had won the election, he would have become Boston’s first Latino mayor.

His fundraising lagged behind most of the other candidates. Santiago pulled in over $700,000 this year, but he was outpaced by Essaibi George ($1.07 million), Wu ($1.01 million), Campbell ($1 million) and Janey ($873,500). Barros has raised $547,532.

Santiago had just over $410,000 in cash on hand at the beginning of July, according to campaign finance filings.

Most of the mayoral candidates still in the running were quick to issue statements praising Santiago.

“I know this decision was not easy for him, but Boston is lucky that it will continue to benefit from his leadership,” Janey said. “I also know that I can rely on him to work with me to create a more equitable, just and resilient Boston.”

Wu said she is “grateful for his contributions to this historic mayoral field (and) to our city,” while Essaibi George called Santiago a “dedicated public servant who has demonstrated his love for this city and its people throughout his entire career and lent an informed and strong voice to this race.”

For her part, Campbell said she is grateful “for the unique experience and passion for service” that Santiago and his campaign brought to the race. “I look forward to continuing to work in partnership to move our city forward,” she added.

"We are lucky he will continue to serve our City and I look forward to working closely with him in the future," Barros said in his own statement.