Stephen Laffey (search), the outspoken mayor of Rhode Island's second-largest city, announced Thursday he plans to challenge fellow Republican Sen. Lincoln Chafee (search) in the 2006 Senate race.

Two Democrats, Secretary of State Matt Brown (search) and former Attorney General Sheldon Whitehouse (search), are also running.

Laffey said Thursday he wanted to give the smallest state in the union "the strongest voice in Washington" and promised to fight big drug companies, big oil companies and special interests, and work for a fairer tax code.

Chafee, a moderate who represents a heavily Democratic state, was mayor of Warwick before he was appointed to the Senate in 1999 after his father, Sen. John Chafee, died. He was elected to a six-year term in 2000.

National Republican leaders have supported Chafee, and other state Republicans have said little publicly about Laffey's expected entry into the race. However, last month, Robert Manning, the party's national committeeman in Rhode Island, said he did not want national party funds spent on candidates until after the primary.

Before being elected mayor in 2002, Laffey was a businessman. Earlier this year, he became embroiled in controversy when he was ordered off his weekly radio talk show by the state Board of Elections, which said the air time amounted to an illegal in-kind campaign contribution.

Laffey, who was not a political candidate at the time, compared the board to the Soviet politburo and sued, saying his free speech rights were being trampled. The board voted to allow him back on the air while it sought clarification from the courts.