SPRINGFIELD (AP) -- Massachusetts Democratic U.S. Rep. Stephen Lynch officially launched his bid for U.S. Senate on Thursday in a part of the state where few voters know much about him, and where the people are generally skeptical of Boston-based politicians.

Lynch, accompanied by some union supporters, and mingling among the breakfast regulars at O'Brien's Corner restaurant on a gray and windy day in Springfield, touted himself as the underdog outsider and played up his working class roots as an iron worker from South Boston.

He even took a shot at a possible Republican candidate, former Sen. Scott Brown.

Brown has not formally announced whether he will run, but fellow Democratic Congressman Edward Markey, has. They are vying to fill the seat left open by John Kerry, who has been named secretary of state in the Obama administration.

The special election will be held on June 25 with a primary on April 30.

"I think if the election were held today, I would lose," said Lynch, calling Markey a Washington insider. "But the election is not today."

He criticized the state's Democratic establishment for throwing its weight behind Markey, the dean of the state's congressional delegation. Voters, he said, deserve a choice.

"Shame on us if we allow someone to purchase the election, without having a choice," he said. "Let the voters of Massachusetts decide."

Lynch said he too drove a pickup truck, just as Brown was seen in campaign ads, but unlike Brown he actually had tools and work boots in his and didn't just drive it back and forth to his law practice.

"I actually slapped on a pair of work boots for 18 years," Lynch said. "I was an iron worker. I think I know what a lot of people are going through right now. I know what it's like to stand in an unemployment line and struggle"

Retiree Kathleen Murphy, 73, a Democratic activist in the western Massachusetts city, said she didn't know much about Lynch or Markey, whose name she couldn't even remember at first. Both represent parts of Boston and suburbs.

"I know very little about him and I'm here to hear his own words who he is," she said.

Lynch was scheduled to continue his tour in Worcester before ending at the iron workers union hall in South Boston.