The city requires that a city manager have support from at least five councillors. Russell and Duehay supported Healy, but once both retire, only three councillors will support hiring Healy for another term.
Russell's retirement also raises questions about her successors. According to the Globe, David P. Maher, a school committee member, will likely run for her seat. Marjorie Decker and Jim Braude, both first-time candidates, may also benefit from the vacancy her retirement creates.
Winters said Russell's decision "wasn't a momentous thing" in her own mind. "She's been telling me every year for six years [that she may not run for re-election]," he said.
"I don't think she has ever looked forward to the campaign aspect," Winters said, adding that many of Russell's top campaigners are "getting older."
Russell said she has no plans for her retirement yet, but that she looks back on her career fondly.
"It's been a pleasure serving the people of Cambridge," she said.
Russell, who is 63, made the announcement on April 27.