A former hospital CEO and a city councillor at-large are the latest contenders hoping to succeed Mayor Thomas Menino.

Savin Hill’s Bill Walczak, who founded the Codman Square Health Center and briefly ran Carney Hospital, confirmed on Monday he is a candidate for mayor.

Jamaica Plain’s Felix Arroyo, who was elected to the City Council in 2009, is expected to announce his candidacy at the offices of SEIU 615 on Tuesday at 10 a.m. The son of a former city councillor, Arroyo once served as the union’s political director.

The moves take them off the list of potential candidates and into the burgeoning field of contenders. Walczak’s entrance into the race was first reported by the Boston Globe on Saturday night.

Walczak said he brings his managerial experience at the Codman Square Health Center and Carney Hospital. He is also the founding president of Codman Academy Charter School.

“I know how to manage, I know how to build teams, I know what it’s like to run a large organization and to be able accomplish things through those organizations,” he said.

Walczak lives in the same neighborhood as another candidate, state Rep. Marty Walsh, a Dorchester Democrat. The chair of his campaign is Donna Gittens of Ashmont Hill, Walczak said.

After his abrupt departure from Carney Hospital, where he was CEO for 14 months, Walczak landed at Shawmut Design and Construction as vice president of community relations.

He also served on a school assignment advisory panel to Mayor Thomas Menino. Walczak was deeply involved in the panel’s efforts to overhaul an unpopular school assignment system.

Walczak said he plans to reduce his hours at Shawmut as the campaign gears up, eventually going into full-time campaign mode.