Catania, who also supported Biddle in last year’s special election, said Biddle “exhibits all the qualities needed to move this city forward.”
Biddle briefly served as an interim council member last year, but was unseated by Orange in the April special election.
Earlier Monday, Biddle also won support from Ward 1 School Board member Patrick Mara.
Neither Mara, a Republican nor Catania, an Independent, will be able to vote for Biddle in the Democratic primary next week.
As the author of the city’s same-sex marriage law, Catania’s endorsement could help Biddle rally gay voters behind his candidacy.
Earlier this month, the Gertrude Stein Democratic Club decided not to endorse a candidate in the at-large race, a setback for Biddle who won the nod last year. The Gay and Lesbian Activists Alliance also rank Biddle and candidate Peter Shapiro as equal in their support of issues of importance to the GLBT community.
Council member Tommy Wells (D-Ward 6) is also publicly supporting Biddle.
Several other council members, including Chairman Kwame R. Brown (D), appear to be staying neutral in the race.