PORTLAND, Maine — Of the three city councilors who stood to take the oath of office Monday, only one was new to the council dais.

Freshly elected Councilor Kimberly Cook joined re-elected council members Jill Duson and Justin Costa at a swearing-in that will likely maintain the balance of power in Portland City Hall.

Cook’s election to the District 5 council seat left empty by David Brenerman, who endorsed her upon announcing he wouldn’t seek re-election in June, is the only change to come out of three competitive council races that, at times, turned bitter, exposing divisions among Portland’s overwhelmingly Democratic political class.

In November, Cook won election by a wide margin in a three-way race, while Duson also bested two challengers to hold her at-large seat and win a sixth term on the city council. Costa was re-elected to represent District 4 for a second term with more than two-thirds of the vote, beating out one other candidate.

Their swearing-in caps a year of discord between Mayor Ethan Strimling and the other eight council members. That strife came to a head in August, when a public meeting brought into full view the long-smoldering conflict between Strimling and City Manager Jon Jennings, as well as revealing the degree to which the councilors had lost faith in a mayor many of them endorsed.

The mayor has since worked to reconcile his relationship with Jennings and the council. He did not endorse any of the three members who took the oath Monday, but struck a conciliatory note in a brief speech welcoming them.

”We must come together to build shared opportunity and inclusive prosperity for [Portland’s] residents,” Strimling said, noting policy items he hopes to see approved in the coming year.

And the mayor and manager were united Monday in their praise of outgoing Councilor Brenerman, who they commended as a leader in city government and an honest, honorable and decent man.

Follow Jake Bleiberg on Twitter: @JZBleiberg.

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