SPRINGFIELD, Mass. — Rep. Stephen F. Lynch officially launched his bid for U.S. Senate on Thursday, setting up a potentially bitter primary battle that Democrats had hoped to avoid in their fight to hold on to the seat of soon-to-be former Sen. John F. Kerry.
Mr. Lynch, accompanied by 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 ironworker from South Boston.
He criticized veteran Rep. Edward J. Markey, who had been considered the front-runner for the Democratic nomination for the special election to succeed Mr. Kerry.
"He's a creature of the Democratic establishment in Washington D.C.," Mr. Lynch said of Mr. Markey, who has served in the House since 1976. "You can't get more insider than that."
Mr. Lynch even took a shot at a possible Republican candidate, former Sen. Scott P. Brown, who has not yet said whether he plans to run.
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," Mr. Lynch said. "But the election is not today."
Mr. Lynch took the state's Democratic heavyweights to task for throwing their support — and fundraising strength -- behind Mr. Markey, the dean of the state's congressional delegation.
"Shame on us if we allow someone to purchase the election, without having a choice," he said. "Let the voters of Massachusetts decide."
Mr. Kerry, who will be sworn in as secretary of state on Friday, is among those supporting Mr. Markey, who also starts the race with a substantial financial advantage — $3.1 million in his campaign account compared to Mr. Lynch's $740,000 as of the most recent campaign-finance reports.
Mr. Lynch also could face a daunting challenge appealing to primary voters who tend to be more liberal than the electorate as a whole.
He voted against President Obama's 2010 health care law, saying it didn't include many of the changes that were in a House version which he supported. He also opposes abortion, though in an interview on Thursday he said he does not advocate for the repeal of Roe v. Wade and has supported funding for Planned Parenthood.
Mr. Lynch, who also visited Worcester and planned to hold a rally at the ironworkers' union hall in South Boston, said he would join Mr. Markey in supporting a deal to keep outside groups from spending money on political ads in the campaign. Mr. Brown and Democratic Sen. Elizabeth Warren abided by a similar "people's pledge" in last year's Senate election.
Mr. Lynch was an ironworker for 18 years before being elected to the state Senate and then to Congress in 2002.
Mr. Lynch said he drove a pickup truck, just as Mr. Brown was seen doing in campaign ads, but unlike Mr. 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," Mr. Lynch said. "I was an ironworker. 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."