Rep. Tammy Baldwin (D-WI), an openly gay congresswoman, announced Tuesday that she would run for the seat Sen. Herb Kohl (D-WI) will vacate upon his retirement in 2012.

Baldwin's name has been floated as a Democratic contender for the seat since mid-May, when Kohl announced his retirement. If she won, she would be the first openly gay U.S. senator. When she won her House seat in 1998, she was the first woman to represent Wisconsin in Congress.

Baldwin announced her candidacy to supporters via email, Metro Weekly reported.

"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," the email read in part. "And I can't wait to see you on the trail as we bring our campaign to every corner of Wisconsin."

A campaign site for Baldwin invites contributions and allows supporters to enter their email address and zip code to "take a stand with Tammy," as more than 6,000 have. The site also has Baldwin's debut campaign video, in which Baldwin name-checks Kohl alongside another popular former Democratic senator from the state, Russ Feingold. In August, Feingold said that he would not run for the open seat, after months of speculation.

"Some folks think America's best days are behind us," Baldwin said in her announcement video. "I'm not one of them. I'm used to facing challenges head-on. When I first ran for Congress in 1998, people counted me out...I want you to know that just like Herb Kohl, I've made standing up for the middle class my top priority."

Both pro-LGBT activist group Human Rights Campaign and the Gay and Lesbian Victory Fund have voiced their support for Baldwin. The HRC called her campaign "monumental" and "a top priority" for their group in a statement.

“Tammy’s election to the U.S. Senate will make history. Added to her long list of firsts, Tammy will be the first woman to represent Wisconsin in the U.S. Senate. Her commitment to equality for all Americans is matched only by her commitment to the people of Wisconsin,” HRC President Joe Solomonese said in the prepared statement.

Watch Baldwin's announcement video below, embedded via YouTube.