City Councilor Richard E. Sullivan Jr. has announced plans to challenge Mayor Donna D. Holaday for the city’s corner office. Sullivan, a retired firefighter, has already pulled nomination papers; the deadline to return them to the city clerk’s office for certification is Aug. 6. He has served on the City Council for one year, but is not a newcomer on the local political landscape. He served on the School Committee from 2001 to 2005 and his family has a long history of public service. His father was a city councilor and served as mayor of Newburyport from 1978 to 1986, and his brothers both served in elected office: Christopher R. Sullivan is a former Newburyport mayor and Joseph P. Sullivan, now a resident of Haverhill, is a former Newburyport city councilor who also served on the city’s Zoning Board of Appeals. Holaday is running for her third term in office. Under the new municipal charter, the next mayoral term will be for four years, paying $98,000 per year.