Oregon Secretary of State Kate Brown, who is widely considered to be to the left of the departing Democratic governor, will become the first openly bisexual governor in the nation. Picture: The Oregonian, Michael Lloyd

Portland, Oregon - Oregon Secretary of State Kate Brown, set to become the nation's first openly bisexual governor on Wednesday, is an under-the-radar liberal Democrat known for her struggles to expand voting and her push for greater campaign finance transparency.

Governor John Kitzhaber resigned his post on Friday amid influence-peddling allegations involving his fiancée that have triggered a criminal corruption probe and led to a frenzy of criticism from prominent fellow Democrats.

“This is a sad day for Oregon. But I am confident that legislators are ready to come together to move Oregon forward,” Brown told reporters in brief remarks outside her office in Salem after Kitzhaber said he would resign, effective on Wednesday.

The resignation gives Brown, whose job is to oversee elections, audits and business registrations, the gift of incumbency in a special election next year.

She had been weighing a bid for governor in 2018 anyway, Oregon media reported.

In addition to becoming the nation's first openly bisexual governor, Brown will also be the second woman to hold Oregon's top elected office.

She has commented publicly about her bisexuality and lives in Portland with her husband.

She was appointed to the state House of Representatives in 1991 when another lawmaker resigned, and in 2004 became the first woman to serve as Senate majority leader, according to a state profile.

Brown has touted her work to create an online database for campaign donations and in passing comprehensive civil rights and domestic partnership laws.

As secretary of state, the 54-year-old backed a bill to register Oregonians to vote when they get a driver's license.

But critics accused her playing partisan politics when she delayed a 2012 election for labor commissioner, a move perceived as helping a fellow Democrat, the Oregonian newspaper reported.

“Her first goal is going to be just to step in and keep moving the state forward, which I think she's uniquely qualified to do,” said Multnomah County Chairwoman Deborah Kafoury, a political ally.

Brown declined to discuss her political agenda with reporters on Friday, and some lawmakers have expressed concern the Portland liberal could be less effective than Kitzhaber at bipartisan politics.

“If Kate Brown wants to lead that party to the left then that's something we're not going to be participating in,” House Minority Leader Mike McLane, a Republican, told reporters.

“I have concern that Portland's left or liberal interests have really risen in the state.”