Stan Rosenberg was first elected to the Massachusetts Senate in 1990, following four years in the state House of Representatives. In 1990, Rosenberg won a special election for the state Senate seat being vacated by Congressman-elect John Olver, for whom Rosenberg had worked as an aide from 1980 to 1983 when Olver was a state Senator.

Rosenberg, who is currently president pro-tempore in the Senate, has been an influential lawmaker on Beacon Hill for more than a decade. In the 1990s, he was chairman of the powerful Senate Ways and Means Committee.

In recent years, Rosenberg has made his mark as a consummate behind-the-scenes player, helping to defeat an amendment last year seeking to ban gay marriage. At the request of Senate President Therese Murray, Rosenberg headed the Senate's study of casino gaming in response to Gov. Deval Patrick's failed casino initiative in 2007 and 2008.

Rosenberg served as a staff member of the Massachusetts Democratic Party from 1983 to 1985, and as the district director for U.S. Representative Chester Atkins from 1985 to 1986. Having spent much of his childhood in foster care, he graduated in 1977 from the University of Massachusetts Amherst and worked at UMass for eight years, first as director of the Arts Extension Service and then as director of the Community Development and Human Service Programs in the Division of Continuing Education.

In 2008, Rosenberg faces a challenge from Republican Keith McCormic, a teacher who works with troubled youth in Holyoke.