That seat is currently held by Mark Sharpe, who will be term-limited out in two years' time.
It will not be Mulhern's first attempt to get elected to the Board of County Commissioners. In her first run for public office in 2006, she lost to Rose Ferlita in the race for the District 1 seat. Several months later, however, she took on incumbent Shawn Harrison for a Tampa City Council seat and narrowly defeated him.
Last year she was easily re-elected to that seat, winning a majority of the votes against challengers Scott Strepina and Susan Long.
In her five and a half years on council, Mulhern has been a consistent progressive voice. Last winter she was the only member of the board to vote against a request by the Tampa Police Department for $2 million in federal funds to pay for surveillance cameras that were to be used for security during last month's Republican convention.
The issue of what to do with the cameras now that the convention is over was discussed for more than two hours at the Council's meeting last Thursday. As her colleagues grew frustrated with the Buckhorn administration's refusal to send a high-ranking official to discuss the plans (the mayor has the ultimate say-so), Mulhern admonished that they should have followed her lead in rejecting the cameras.
Currently the Board of County Commissioners is controlled by Republicans, with the seven person body having only two Democrats. In 2010 both Linda Saul-Sena and John Dingfelder, who often voted along the same lines as Mulhern on the City Council, were defeated in their attempts to move from the city to the county.
But Mulhern expressed no concerns about making the transition, saying she will campaign to win the support of everyone in the large county.
"In my five and a half years on the council, I’ve served my constituencies not knowing what party they belong to," she said, adding that she has a lot of support across the political aisle. "I wouldn't be running if I didn’t feel confident if I didn’t have a good chance of winning."
This is the earliest Mulhern has ever announced her candidacy. She said she will speak more about her intentions after the November election.
Meanwhile, Mark Sharpe has not given any indications of what lies in store for him when his term ends in two years. In 2011, he announced that he would challenge Democrat Kathy Castor in her bid for re-election for Congress, but earlier this year changed his mind, saying that it was hard to fundraise against a popular incumbent in a district that is heavily Democratic.