US congresswoman Tammy Baldwin has entered the race to win retiring Wisconsin senator Herb Kohl’s seat in 2012.

If she is successful, she will become the first openly LGBT senator.

Ms Baldwin, a Democratic representative for Wisconsin, is one of just four openly gay congress members. She is the only lesbian in congress.

In an email sent to supporters this morning, she wrote: “I can’t wait to take my fight to the Senate: a fight to grow our economy, protect seniors, force Wall Street to clean up its act, and bring our troops home from Afghanistan.

“And I can’t wait to see you on the trail as we bring our campaign to every corner of Wisconsin.”

She added: “I know that, in this campaign, we’ll be up against some powerful special interests.

“But I’ve beaten the odds before. All my life, the naysayers have told me that I can’t win because I’m a progressive…because I’m a woman…even because I’m a lesbian. And I’ve proven them wrong because I’ve had rock-solid supporters like you standing with me.”

Speaking to the Milwaukee Journal Sentinel, she said: “I’ve been honest about my sexual orientation my entire adult life, and integrity is important in public service.”But what voters are looking for is somebody who understands them…the election is not going to be about me.”

One of her Republican rivals, Mark Neumann, has a history of anti-gay remarks, including saying in 1996 that he would make homosexuality illegal.

According to the Washington Blade, he said in 1997: “If somebody walks in to me and says, ‘I’m a gay person, I want a job in your office,’ I would say that’s inappropriate, and they wouldn’t be hired because that would mean they are promoting their agenda.

“The gay and lesbian lifestyle [is] unacceptable, lest there be any question about that.”

Joe Solmonese of the Human Rights Campaign said: “Tammy Baldwin’s candidacy for the U.S. Senate is monumental for both the state of Wisconsin and the country’s LGBT community.

“Tammy has proven herself as an effective legislator over the course of her 13 years in Congress and this campaign will be a top priority for the Human Rights Campaign.”