SALEM, Ore. » Kate Brown took the oath of office as governor here on Wednesday, capping a decadeslong climb through the ranks of state government but also commencing what is certain to be a wrenching transition fraught with political risk. Her predecessor, John Kitzhaber, announced his resignation last week, just weeks into his fourth term, amid an onslaught of criminal and ethical investigations and a collapse of support from his own party.

Brown, a Democrat like Kitzhaber, who as secretary of state was the first in line to succeed him under Oregon’s Constitution, has promised to make a series of immediate moves that she says are “needed to restore the public’s trust in government.” She also said she would address economic issues facing working families.

The swearing in of a new governor also brings a kind of cultural shift to the state capital. Kitzhaber, 67, a former emergency room doctor, forged his political identity as a moderate Westerner, usually in boots and jeans, who often reached out to the state’s rural and more conservative areas, which have struggled economically.

Brown, 54, by contrast, is more a product and a reflection of the state’s largest and perhaps most liberal city, Portland. She is a yoga enthusiast and a cyclist who often rides tandem with her husband, Dan Little, from their restored early-20th-century home in southeast Portland. She is also bisexual, having come out in an essay on a website about elected officials who are “out,” and is being recognized by gay rights groups as the first openly bisexual governor in the nation.

Brown was born in Spain, where her father was serving in the Air Force, and grew up in Minnesota. She earned her undergraduate degree from the University of Colorado Boulder, and her law degree at Lewis & Clark College in Portland.

Her sexual identity became part of her political stamp while she was in the state Legislature, where she focused in part on pushing economic and health legislation aimed at women. She served there for 17 years before seeking statewide office.

Her career has not been without criticism.

The Oregonian, the largest newspaper in the state as well as Brown’s hometown paper, endorsed her Republican opponent in her re-election race for secretary of state in 2012, partly because she had delayed an election — elections are a function of the secretary of state’s office — in ways that seemed, the paper said, politically calculated to help a Democrat.

“Brown is a smart, energetic official with a long record of public service,” the paper said in its endorsement. “But she’s had her shot at this office, and it’s time for a change.”

She won a second term that year anyway, with 51 percent of the vote.

Brown got a black eye last month, though, when the online publication The Verge, citing email records, said she was among a group of politicians around the country who had sent letters supporting the cable giant Comcast’s merger with Time Warner Cable — letters that had been drafted, the paper said, by Comcast itself, which had contributed to Brown’s political campaigns, the article said.

The mayor of Portland, Charlie Hales, said in a statement that he believed Brown had demonstrated her ability to handle tough times.

“The challenges ahead of her are enormous, and she is exactly the right person, at the right time, to take them on,” Hales said. “I have great faith in Kate Brown as a partner in governance, as a civic leader, and as a Portlander.”

Brown will come before voters as governor in her own right in a special election next year, and if she wins, she could run for a full four-year term in 2018, when Kitzhaber’s term would have expired.

In socially liberal Oregon, her sexual orientation is unlikely to raise much of a fuss, and in some areas, it could probably be a plus.

“I just learned that she’s bisexual,” said Jared Dahle, 28, who works as a window cleaner and in a bar in Portland. “That’s cool.”

Dahle, who is gay, said he had met Brown a few times when he was working at a hotel and she came in for meetings. He said what struck him then was that she always spoke to him, something not all politicians did. “I’m optimistic about her,” he said.

Little, Brown’s husband, is an outdoorsman who has worked for the U.S. Forest Service, giving her the opportunity to regularly visit rural parts of the state. She served in the Legislature during periods when Democrats did not control both chambers, as they do now.

As a legislator, Brown worked on an ethics law overhaul and with a bipartisan group that passed legislation making campaign contributions more transparent by creating an online database for reporting.

Kitzhaber announced his resignation on Friday as criminal investigators were looking into the business dealings his fiancie, Cylvia Hayes, had with his administration.

In a simple ceremony in the state Capitol, Brown was sworn in as governor on Wednesday, and her remarks to the Legislature afterward were brief and low on specifics, although she said she would push for stronger powers for the Government Ethics Commission.

She mentioned Kitzhaber just once — to praise him, faintly, and damn him, a bit, in the same breath.

“Gov. Kitzhaber dedicated most of his life to serving the people of Oregon,” she said. “His contributions to our state are well woven into the fabric of our public life. But now we must restore the public’s trust.”

Ginny Burdick, a Democratic state senator and longtime colleague of Brown’s from Portland, said the sudden transition in power was “a very shocking thing for our political process.” But she added that Brown’s diversity of experience was a big advantage, giving her a perspective few have had on becoming governor.

“You couldn’t have invented somebody who has a better chance of actually making this work,” Burdick said.