The Portland City Council appointed deputy city manager Sheila Hill-Christian as acting city manager as expected Wednesday night, and city officials said they will proceed with efforts to fill three vacant department head positions within City Hall.

The Portland City Council began the process of replacing City Manager Mark Rees, who stepped down Wednesday, by naming members of a search committee and discussing plans to hire an outside search firm.

Hill-Christian, who already oversees several large city departments including Health and Human Services and the Police Department, joined city staff in February 2013 and will earn the salary paid to Rees, $146,598.

Five councilors stood up to praise Hill-Christian for her service during her roughly 18 months with the city, marking her as a potential contender to replace Rees.

Councilor Jill Duson said one thing Rees did well was hire talented city employees, and she called Hill-Christian “one of the best hires.”

Hill-Christian was given the authority to move forward with the search to fill three top posts within city government: the directors of the departments of finance, human resources, and health and human services.

Candidates already have been identified for the health and human services as well as human resources positions through the use of a search firm.

“They happen to be excellent candidates and we are concerned that some of them may be driven away” if the search process is suspended, Hill-Christian told councilors after a closed-door discussion of the issue. The search for a human resources director was put on hold after Rees’ decision to step down.

Last month the city announced Rees’ resignation effective Wednesday, roughly three years after he left a similar post in North Andover, Mass., to take over Portland’s top administrative job. Rees said in a letter to city councilors that he planned to “pursue other opportunities, both professional and personal,” but he did not elaborate.

Rees did not attend Wednesday’s workshop or council meeting.

The city received 65 applications during the last city manager search that led to Rees’ hiring in 2011. The position is expected to draw strong interest this time as well, although it was unclear Wednesday how wide a net the committee and search firm will cast.

Members of the search committee – Mayor Michael Brennan and Councilors Jill Duson, Nicholas Mavodones and Ed Suslovic – are expected to discuss the scope of the search during the first meeting.

During the last search, the city held a public meeting with the three finalists in order to allow local residents to meet the candidates. The decision to publicly identify finalists prompted at least one candidate to withdraw from consideration.

“Last time everybody worked hard to keep as much as we could out there for the public to see. The other thing is I hope we can be as expedient as possible as a council in trying to move this process forward. We have a pretty good sense, given that we had a search not too many years ago.”

Portland corporate counsel Danielle West-Chuhta said it was too early to say how much it will cost to hire an outside search firm. West-Chuhta said the fee will depend, among other things, on whether the firm or the committee will vet the initial pool of candidates.

Rees resigned several months after the City Council voted to extend his contract by just one year, compared to the initial three-year contract. Some observers interpreted that as a potential sign of unease between council members and Rees, although several councilors have said in recent weeks that they did not ask him to step down.

Council members credited Rees with a number of accomplishments, including crafting a five-year, $92 million capital improvement plan – a first for the city – and streamlining the development review/permitting process at a time of significant, post-recession growth.

Rees also presented three balanced budgets and helped fill several key positions, including the planning director, the police and fire chiefs and Hill-Christian, his deputy city manager and at least temporary successor.

But Rees’ tenure as city manager coincided with a significant shift in the structure and dynamics of governance within City Hall. Following charter changes approved by city voters in 2010, Brennan became the first elected mayor in nearly 90 years and became both the city’s top spokesman and policy agenda-setter. Rees largely stayed out of the spotlight as he managed the day-to-day activities of City Hall.

There were growing pains associated with the transition, however, primarily between Brennan and the other eight City Council members who now had less frequent contact with Rees than the new full-time mayor.

Hill-Christian joined the city staff in February 2013, filling a new role as deputy city manager that assumed many of the responsibilities previously handled by two assistant city managers. Before moving to Maine, Hill-Christian ran a consulting group in Virginia that worked with municipalities and nonprofit agencies. She also served for a time as chief administrative officer as well as chief of staff to the mayor of Richmond, Virginia’s capital city with a population of more than 200,000 people.

Brennan, who appeared to enjoy a more positive relationship with the outgoing city manager than other councilors, was the only council member to publicly thank Rees for his time in the city.

“I think he left the city better off and I personally and professionally wish him well in his future endeavors,” Brennan said.