Associated Press
Rep. Barney Frank, D-Mass. gestures during his news conference on his retirement, Tuesday, Nov. 29, 2011, on Capitol Hill in Washington. (AP Photo/Pablo Martinez Monsivais)

BOSTON — Rep. Barney Frank's decision to step down at the end of his term is the latest jolt to the bruised ego of the Massachusetts Democratic Party, which once counted Kennedys, House speakers and a president among its ranks.

Instead, some of the state's best-known political figures are now Republicans, among them Sen. Scott Brown and presidential candidate Mitt Romney.

"For a long time, Massachusetts Democrats have felt they played a special role in the national Democratic Party," said Tufts University political science professor Jeffrey Berry. "I think that has gone at this point. There is no one in Congress from Massachusetts who has that stature now."

Frank has long been a liberal lightning rod and is the highest-profile member of the state's all-Democratic House delegation. His announcement follows the decision of another Massachusetts representative, John Olver, a member of the House Appropriations panel, not to seek re-election.

Add to those impending departures the death of Sen. Edward Kennedy in 2009 and the state's loss of a House seat in the most recent redistricting process, and some Democrats in Massachusetts are wondering whether the glory days are behind them.

While the state's senior senator, John Kerry, has a powerful perch as chairman of the Senate Foreign Relations Committee and often serves as a troubleshooter across the globe for the Obama administration, there's been plenty of speculation that if Obama wins re-election, Kerry could be tapped to succeed Secretary of State Hillary Rodham Clinton.

That would rob Massachusetts of a strong Senate presence.

Part of the decline is due to inexorable demographic changes that are working against the relatively small Northeastern state.

While Southern and Southwestern states have experienced population booms, Massachusetts has seen anemic growth, leading to the loss of one of its 10 seats in Congress.

The prospect of running in a newly redrawn district with 325,000 new constituents, combined with the Democrats' loss of control of the House, prompted Frank's decision not to run again after more than three decades in Congress, the 71-year-old said.

"One of the advantages to me of not running for office is that I don't even have to pretend to be nice to people I don't like," the famously acerbic Frank said.

There was a time not so long ago when Massachusetts Democrats held outsized political sway in Washington.

That power may have reached a high water mark during the country's post-World War II years. Massachusetts politicians held the powerful post of House speaker for nearly 20 years, first under John McCormack from 1962 to 1971 and then again under Thomas P. "Tip" O'Neill, who wielded the gavel from 1977 to 1987.

During that same span, another Massachusetts Democrat — John F. Kennedy — was elected president, and his brother Edward began what would be a nearly half-century of service in the Senate.

Even as the nation's population growth shifted away from the Northeast, Massachusetts Democrats still harbored big political dreams. Both Kerry and former Gov. Michael Dukakis won the Democratic nomination for president but lost in the general election.

One reason Massachusetts Democrats gained power in Washington is that they were able to easily win election again and again at home, giving them prized seniority on congressional committees, according to Berry.

Before Republicans won control of the House, Frank was chairman of the House Financial Services Committee and was key in crafting the Dodd-Frank bill, which contained the stiffest restrictions on banks and Wall Street since the Great Depression.

"That's the real loss, because committee chairs have enormous power to push projects and send money into various accounts that will help their home districts," Berry said.

Not everyone is ready to consign the state party's best days to the history books.

Massachusetts Democratic Party chairman John Walsh concedes the departure of Frank and Olver and the death of Kennedy are blows — but are also part of the inevitable progression of politics.

He said the strength of the Massachusetts Democratic Party is the depth of its political farm league.

"We keep electing good strong, capable Democrats. We constantly have a stream of our leaders who are moving up the line," Walsh said.