Kotek's selection is another key political victory for the gay community that has notched successes around the nation. It still has to be formally ratified in January.
Kotek said she didn't set out to break barriers but is honored to represent the gay community.
"We all look for people out there who look like us," she said. "I have had emails and text messages from people who are very excited."
Openly gay leaders will control the House or Senate in five states -- more than ever before, and up from two before last week's election.
"For many years, we were building a bench of openly gay officials who could step into those roles, and now we're seeing that around the country," said Denis Dison, a spokesman for the Gay and Lesbian Victory Fund, a national group that helps gay candidates get elected to offices at all levels.
The organization backed 180 candidates this year, and 122 won office, Dison said.
Kotek has represented a liberal district in the heart of Portland since 2007. She became the No. 2 leader in the Oregon House in 2011 when her Democratic colleagues ousted her predecessor after a legislative session that left many of them frustrated by Republican successes.
She oversaw campaign efforts that helped her party pick up four House seats on Nov. 6 and grab the majority in the chamber.
Oregon Democrats also chose Rep. Val Hoyle of Eugene to be majority leader, the No. 2 position in the House.
Elsewhere, Arizona Democrat Kyrsten Sinema will be the first openly bisexual member of Congress, and at least five openly gay Democrats were elected to U.S. House seats.
Wisconsin congresswoman Tammy Baldwin became the first openly gay person elected to the U.S. Senate.
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