On Tuesday, Martha Coakley lost to Scott Brown in their race for a Senate seat once held by Lodges and Kennedys. Other losers were Barack Obama, Ted Kennedy’s legacy, the Democratic Party’s stranglehold over Massachusetts, and, most consequentially, perhaps health-care reform. To put the victory into local perspective: every statewide officeholder, as well as every Massachusetts representative in Washington, is a Democrat. Of the Bay State’s ten seats in the House of Representatives, Republicans contested just four in 2008—not breaking 30 percent of the vote in any of those races. A Republican hasn’t won a Senate seat representing Massachusetts since 1972. Both houses of the state’s legislature, the General Court, have been under Democratic control since the 1950s. Democrats outnumber Republicans three to one in voter registration. So how did Martha Coakley snatch defeat from the jaws of victory in what may be America’s bluest state?

For starters, her parents must have forgotten to read her “The Tortoise and the Hare.” Thirty points ahead in November, Milk-Carton Martha went missing between Christmas and New Year’s. Brown capitalized. An ad that cleverly depicted JFK morphing into Brown, portraying the Republican as the heir to the Democratic icon’s tax policies, peeled away Democrats from their ancestral home (Rasmussen estimates that 22 percent of Democrats voted for Brown yesterday). During the same crucial week, Brown, a state senator, introduced symbolic but commonsense legislation that sought relief from onerous taxation and spiraling health-care costs. All the while, Coakley appearances were as sketchy as Elvis sightings. When asked about her somnambulant manner of running for office, Coakley quipped, in a derisive reference to Brown’s campaigning at an outdoor Boston Bruins game: “As opposed to standing outside Fenway Park? In the cold? Shaking hands?” Even when you’re a heavy favorite, you don’t run out the clock. Martha Coakley inexplicably did just that.

When Coakley did show her face, her prospects didn’t improve much. With the charisma of C3PO and the foreign-to-Massachusetts accent of Martha Stewart, Coakley cut an alienating figure on the campaign trail. Brown was once named “sexiest man in America” by Cosmopolitan, is married to a popular local newscaster, and has two beautiful daughters; Coakley is married with dogs. Voters didn’t connect. Her gaffes included contending that terrorists no longer resided in Afghanistan, urging devout Catholics to go into a line of work other than emergency-room medicine, and labeling Red Sox hero Curt Schilling a “Yankee.” To know Martha was not to love her.

Coakley’s party label may have been, strangely, as much albatross as asset in 2010. With one House speaker facing 180-plus years in prison for corruption and his two predecessors convicted felons, Bay State voters may have reached a tipping point. A crime wave by state legislators—including one allegedly caught on video stuffing a bribe into her bra—reminded voters of the culture of corruption that one-party states invariably breed. It wasn’t merely guilt by association, either: Coakley is the state’s attorney general. The Massachusetts malfeasance has been investigated and prosecuted exclusively by the feds. That speaks volumes.

Still, Massachusetts didn’t just recently become Louisiana North. During the first half of the twentieth century, “Vote early and often for Curley” was the unofficial campaign slogan of Boston felon-mayor James Michael Curley. And the state’s Democrats have run horrible campaigns in the past. The consequences for party corruption and lackluster politicking have rarely included defeat. What changed?

Tuesday’s stern rebuke can be directly tied to Barack Obama’s overreach. The president misread his victory over a weak John McCain, tethered to an even weaker Bush administration, as a mandate for European-style socialism. Brown’s position in the U.S. Senate, as the 41st vote upholding any Republican filibuster of the legislation that would increase the government’s involvement in health care, is both symbol and substance. His victory reflects popular disgust over the president’s health-care plan. If this message isn’t a strong enough warning to Democrats to abandon the White House policies that are bringing them down, then Brown’s vote in the Senate may alleviate them of the burden of having to vote on a final bill. Scott Brown’s victory can be a harbinger of things to come or a wake-up call for congressional Democrats. It’s their decision.

In a word, arrogance defeated Martha Coakley. Should her loss prove a dress rehearsal for November’s midterm elections, arrogance will again be the reason for a Democratic defeat. In fact, instead of learning from such a devastating defeat on their home turf, Democrats are mulling over a delay in seating Brown and discussing ways to pass ObamaCare through filibuster-proof procedures normally reserved for budget reconciliation. Coakley’s loss should be a signal warning for Democrats to hit the brakes. Instead, they have pressed harder on the gas.

Tuesday’s election overflows with ironies. The very Senate seat occupied by the institution’s most dogged advocate of universal health insurance will become the vote that could block the health-care plan. The nation’s bluest state has held up the brightest red flag to President Obama’s agenda. Massachusetts, which instituted the model for ObamaCare, may become the state that ultimately derails it. And finally, the Democrats’ heavy-handed shenanigans—battling to change the rules to enable the state’s Democratic governor to appoint Kennedy’s replacement, just five years after they had stripped a Republican governor of the same power—actually helped doom their candidate. If the party had left well enough alone, the contest would likely have taken place a month ago, and Coakley would have cruised to victory.

“If I don’t win, 2010 is going to be hell for Democrats,” Coakley predicted. “Every Democrat will have a competitive race.” She called it. If Democrats aren’t safe in Massachusetts, they aren’t safe anywhere.

Daniel J. Flynn, author of A Conservative History of the American Left, resides in Massachusetts.