Massachusetts voters fired the shot heard ’round the country on election night. Scott Brown’s victory topples the Democrats’ tenuous Senate majority and poses a real threat to President Obama’s legislative agenda. And in a crucial election year, his historic upset in a state that hasn’t elected a Republican senator since 1972 is cause for panic for Democrats.

Massachusetts voters fired the shot heard ’round the country on election night.


Republican Scott Brown’s victory topples the Democrats’ Senate filibuster-proof majority and poses a real threat to President Obama’s legislative agenda. And in a crucial election year, Brown’s historic upset in a state that hasn’t elected a Republican senator since 1972 is cause for panic among Democrats.


“You can go right down the list of major controversial issues on the Obama agenda and see very clearly that this election will have profound consequences,” said Phil Johnston of Marshfield, former chairman of the state’s Democratic party and a veteran lawmaker.


Without its 60-vote supermajority, Senate Democrats may have to scale back White House priorities to gain bipartisan support or risk being blocked by the GOP.


“We’ve had a monopoly in Washington for the last year with one party controlling Congress and the White House. Folks here in Massachusetts understand what that means,” said Charles Manning of Hull, a former state GOP chairman.


In addition to health care reform, key issues ahead include a proposed cap-and-trade program to control greenhouse gases and a proposed tax on banks that received bailout money – two bills Brown has said he will not support.


Early Tuesday, House Democrats signaled they may be willing to vote on the more conservative Senate version of the health care bill without making amendments – a course that would fast-track it before Brown can take his seat.


But while Washington Democrats may view Brown’s victory as a roadblock, Massachusetts voters appeared confident that putting the brakes on the Democrats’ course was necessary – both for the state and the country.


Many South Shore voters said an otherwise predictably blue state was sending a wake-up call on the need for change and balance.


Joy Cox, 71, of Quincy, who voted for Brown, said his win “ will bring things back into perspective. A change will bring a better balance to this state.”


After voting for Brown at the Talbot School in Weymouth, John Murphy, 63, said, “This is a message for Mr. Obama. I don’t think we can afford his health care bill. ... It seems like he is trying to stuff it down our throats.”


Massachusetts voters also sent a message to Democrats throughout the country facing mid-term elections this fall, and to incumbents statewide, including Gov. Deval Patrick.


“If you’re a Democrat or a Republican, you better start paying attention and listening to the people you represent,” Manning, the former GOP state chairman, said. “Nothing frustrates voters more than when they’re sending a clear signal to their elected leaders and their leaders say, ‘We know better.’”


Nancy Reardon may be reached at nreardon@ledger.com.