The Jan. 19 election to succeed Paul Kirk - and Ted Kennedy - in the United States Senate was supposed to be the tripwire. The vote that launched a thousand domino campaigns, Democrats vying against Democrats for seats long held safe by Democrats, and expected to be held by Democrats long into the foreseeable.

Instead, state Sen. Scott Brown's election over Attorney General Martha Coakley has sent the state's plurality party into an unaccustomed place: the wilderness contemplative.

The last time the Dems were here was 2002, when a venture capitalist and Olympic organizational hero named Mitt Romney had just dispatched a state treasurer named Shannon O'Brien, on a count of 50 percent to 45 percent, in the gubernatorial election. Enough, top Dems said, of holding staggering advantages in the voter registration rolls and never, not in 12 years, the governor's office.

A commission was formed. Post-mortems were conducted. Theories of the case were authored. The introspection is much broader this time around, the teeth-gnashing much more frantic. It is now a national problem, not just the frustrated desires of some state senators and state reps.

Locally, of course, the immediate concern is November. The incumbent lawmakers who had once thought they were safe - who even after New Year's Day thought Martha Coakley was secure - are now questioning how they'll spend their summers and falls. If a little-known state senator can unhorse the state's fourth woman elected to outside office despite her commanding lead with weeks to go … who's OK?

There were, again, theories. From opposite tips of the Democratic Party, two senators held forth.

Sen. James Eldridge, perhaps Gov. Deval Patrick's favorite member of the Senate, circulated an e-mail to colleagues in the days after the election. Sen. Steven Baddour, perhaps the governor's least favorite member even before the testy face-to-face they had near the end of 2008, published an op-ed in the Eagle-Tribune.

Eldridge said voters were clearly peeved: "They're angry about a lack of visible progress, deals made behind closed doors, and giveaways to corporate special interests." Baddour concurred: "Taxpayers, who feel nickel-and-dimed by government, are paying far more of their hard earned dollars for fewer services, while special interests and wasteful programs continue to receive more and more … Criminal behavior, back-room deals, and lack of true accountability have disenfranchised the voters and left them with a destructive and cynical view toward government."

Eldridge was less specific - he proposed no new bills, and opposed no old ones. Baddour was a little tauter: no new taxes, less spending. Both wanted job creation.

Baddour, Democrat of Methuen: "It would be foolish to ignore that a major reason a Democrat didn't win the seat formerly held by the late Sen. Edward M. Kennedy is because the Democratic Party has lost touch with the concerns of the majority of voters in Massachusetts … Democrats must realize that they cannot tax themselves into a recovery because we are reaching a point where the private sector can no longer afford to subsidize the public sector and vice-versa."

Eldridge, Democrat of Acton: "The answer, I believe, is to do more to help working families get, and stay, on their feet. We need to work even harder on a range of important issues - from housing and foreclosure issues to job creation, consumer protection, health care, and environmental protection - to show our constituents that we are taking action to make a positive difference in their lives."

Republicans, meanwhile, have their own dilemma, not unlike the one delivered to the Manhattan Project upon reaching its discovery: What do we do with THIS?

In all likelihood, Brown's victory will result in a recharge of lower-office candidates for the GOP. But, Republican strategists said, if the effort resembles Romney's "Team Reform" bid, the failed effort in the 2004 elections to erode the Democratic majority, the long-term progress for the minority will be negligible. What the party needs, they said, are serious candidates for legitimately imperiled seats.

Mathematics holds that the Democrats, even in disarray carried to the extreme, could not cough up their legislative majority, even if the shut-outs in the U.S. House delegation and the constitutional office ranks erode.

Still the various and competing exertions on where the state party goes from here - toward Eldridge, and a sturdily progressive agenda, or toward Baddour, and a largely centrist emphasis on fiscal conservatism - stands to define not just the remainder of 2010, but how Democrats view themselves in the new political climate of Scott Brown's Massachusetts.