Scott Bartley was elected mayor of Santa Rosa by his council colleagues Tuesday night in a split vote decided by newcomer Erin Carlstrom, who then cast the deciding vote for herself as vice mayor.

Carlstrom, a 29-year-old attorney, acknowledged the difficult decision she faced being the swing vote between Bartley, an architect who favors less government regulation, and Gary Wysocky, whose tends to side more with environmental, labor and neighborhood interests.

"To be blunt, there is no simple answer on this vote," Carlstrom said.

The decision was one of intense speculation among council watchers who said they had little hint of whom Carlstrom would support.

By backing Bartley she risked angering the progressives who supported her early in her campaign. But by siding with Wysocky she risked upsetting public employee unions who worried Wysocky would demand greater concessions, while some business leaders felt he wasn't sufficiently pro-growth.

In explaining her vote, Carlstrom said she felt the only way the council would be able to tackle all the issues facing it was if council members trusted one another and worked together.

"The mayor holds no more say over the future of our community than the other council members up here today," Carlstrom said, "but will need to set aside his or her personal beliefs and interests to ensure the rest of the council is able to shine."

Without saying anything against Wysocky, Carlstrom said she believed Bartley was the best positioned to lead the council forward.

"I believe councilmember Bartley will rise to this occasion and to this charge, to lead this council which is a drastically different council politically than any that I am aware of," Carlstrom said.

"I am committed to working with him and the rest of the council to move Santa Rosa in a new direction."

The vote was 4-3, with Mayor Ernesto Olivares, Jake Ours, Bartley and Carlstrom backing Bartley, with Wysocky, Susan Gorin and Julie Combs voting against him.

After the vote, Olivares got up and shook hands with Bartley, handing him the official gavel. Bartley said he hoped the council could find ways to be more collaborative, much like the period when he served on the planning commission.

"None of us are here to be miserable," Bartley said. "A lot more can get accomplished if we really work together in a positive way, and that is my goal."

Carlstrom's decision confirmed the fears that progressive groups began to have after she and Olivares cross-endorsed once another in late September. Both said it was an effort to change the tone on the council, which has been sharply divided along ideological lines for years.

But environmental and neighborhood groups that supported Carlstrom early in her campaign were aghast by the move and questioned her allegiance.

"I'm definitely disappointed," Dennis Rosatti, executive director of Sonoma County Conservation Action, said after the meeting. "I thought we shared values and goals."

He noted that his group had always given Wysocky "A" ratings on the environment, while Bartley received a "C-minus."

"It's going to be an interesting two years," Rosatti said.

But others were pleased with Carlstrom's decision. Keith Woods, chief executive officer of the North Coast Builders Exchange, said "she showed a lot of guts."

"I think she did the right thing for the city, but it must have been tough," Woods said.

Woods said Wysocky "has been considered to be prickly," while he considered Bartley easy to work with and predicted he will be "more of consensus builder."

After the meeting, Wysocky said he was disappointed.

"It'll be a challenging two years. I look forward to offering my insight to the council," Wysocky said.

Following the vote for mayor, Carlstrom and Combs were both nominated for vice mayor. Combs couldn't get four votes, but Carlstrom got five, including her own and the support of Gorin.

Earlier in the meeting, outgoing council members Marsha Vas Dupre and John Sawyer both expressed their thanks to city staff and for the opportunity to serve.

"It has been a very, very rewarding experience, one that I will cherish for the rest of my life," Sawyer said.

You can reach Staff Writer Kevin McCallum at 521-5207 or kevin.mccallum@pressdemocrat.com. OnTwitter @citybeater