For Democrats, it is officially time to worry. The party’s gubernatorial losses in Virginia and New Jersey last fall could be partially explained away as the states’ usual off-year swing to the “out” party.

But Republican Scott Brown’s come-from-behind victory last week in the special Massachusetts Senate election for Ted Kennedy’s Senate seat is something else – a harshly delivered slap in the face from voters in one of the most loyally Democratic states in the country.

In short, what we have right now is not an aberration, but a trend – and a very negative one for the Democrats. The enthusiasm gap that favored Barack Obama and the Democrats in 2008 has shifted to his opponents. The independents that buttressed Democrats in the last two election cycles have moved in large numbers to the other side. And President Obama has been unable to stem the tide, even with the investment of his political capital into each losing campaign.

A look at the numbers shows the sharp reversal of fortune that has taken place in the last year. Obama swept Virginia, New Jersey and Massachusetts in the 2008 presidential balloting by a combined margin of more than 1.5 million votes. Since then, Republicans have won the major statewide races in the three states by an aggregate plurality in excess of 500,000 votes.

When viewed on a state-by-state basis, the recent results appear even more distressing for the president and his party. In Massachusetts, Martha Coakley’s 47 percent share of the vote was the lowest for a Democrat in a Bay State Senate race since 1972. In New Jersey, Gov. Jon Corzine’s 45 percent showing last November was the second-weakest for a Democratic gubernatorial candidate there since 1969. And in Virginia, Creigh Deeds’ tepid 41 percent vote share in 2009 was the second lowest for a Democratic candidate for governor in the Old Dominion since Reconstruction nearly a century and a half ago.

Chart 1. Recent Democratic Defeats Not Historically Unusual, But Margins Are

It is no embarrassment for the president’s party to lose the off-year gubernatorial elections in Virginia and New Jersey. Over the last decade or two it has become the norm. But the falloff last fall in the Democratic vote in the two states, plus Massachusetts, the site of this month’s special Senate election, has been eye-catching. The party’s share of the gubernatorial vote in 2009 was down a dozen percentage points from Barack Obama’s 2008 presidential vote in each state. And in Massachusetts, the Democratic proportion of the Senate vote was down 15 points from Obama’s ’08 showing. At no time during the presidency of George W. Bush did the Republican gubernatorial vote in Virginia and New Jersey decline more than 8 percentage points from the previous GOP presidential vote in the state.

Sources: America Votes (CQ Press) for election returns through 2008; web sites of New Jersey and Virginia election authorities for official results from the 2009 gubernatorial races; for the nearly complete but unofficial results from the Massachusetts special Senate election.

In none of the three elections did Democrats come close to reassembling the broad Obama coalition, even within the parameters of a lower turnout election.

In Massachusetts, for instance, the 2008 presidential election map looked like a sea of blue, with little more than a few clusters of towns voting for Republican John McCain. The map for last week’s open Senate election was starkly different. As David Filipov of the Boston Globe wrote, Massachusetts became a microcosm of the country as a whole: “blue on the edges with a big red swath in the middle.”

Coakley won not much more than the immediate Boston area and the lightly populated western portion of the state, with its college towns and artistic communities. The bulk of the rest of the state – Boston’s outer suburbs, towns from Cape Cod to the center of Massachusetts, and even an old blue-collar mill town or two – bolted to Brown.

The Republican carried Lowell, a once thriving textile center and home to the late Democratic Sen. Paul Tsongas. He won the town of Barnstable, which includes the Kennedys’ homestead at Hyannis Port. And Brown swept independent-minded Marlborough, a town about 25 miles west of Boston that was featured in an election-eve article in The New York Times as “the kind of place where many Massachusetts elections are won and lost these days.” Obama carried Marlborough in 2008 with 57 percent of the vote. Brown won it last week with an identical 57 percent.

As for the Obama coalition, only the liberal wing held fairly firm for Coakley. While she ran 15 percentage points worse than Obama statewide, Coakley was down only 3 or 4 points in leftish academic centers such as Amherst and Cambridge and the gay-friendly resort town of Provincetown on the tip of Cape Cod.

But the falloff was dramatic in other parts of the Obama constituency. In Boston, the state’s major urban center with a population nearly one-half non-white, Coakley ran 10 points below Obama. In Lawrence, which is majority Hispanic, the falloff from 2008 was 15 points. And in other historic industrial centers such as Brockton, Fall River and Lowell, the decline was 15 points or more from Obama’s showing barely a year earlier.

Compounding the problem for Coakley was that the turnout was generally low in traditional Democratic strongholds, while much higher in places that voted for Brown. Statewide, the Boston Globe calculated that about 54 percent of registered voters cast ballots in the Jan. 19 Senate election. But turnout was just 47 percent in academic-oriented Amherst, 43 percent in multi-racial Boston, 38 percent in blue-collar Fall River, and a mere 28 percent in Hispanic-majority Lawrence.

At the other end of the turnout scale, the Globe found 27 towns that had turnouts of 70 percent or higher, 20 of which voted for Brown. This came in spite of an eleventh hour trip by Obama to Boston to fire up the Democratic base. His spirited speech served as Coakley’s closing argument. But as in Virginia and New Jersey, the president’s campaign efforts did not come close to producing a Democratic victory.

Chart 2. Democrats Finding It Difficult to Reassemble the Obama Coalition

Since the presidential election of Barack Obama in 2008, Democrats have found it difficult to reassemble the elements of his successful coalition. In this month’s Massachusetts Senate election, Democratic candidate Martha Coakley was largely able to hold the liberal wing of the coalition found in academic communities and resort areas. But there was a dramatic falloff in the Democratic vote from 2008 in the old blue-collar mill towns of Massachusetts as well as politically marginal communities from Cape Cod to “Middle Mass.” The latter is the host of towns outside the orbit of Boston that anchor the center of the state.

Note: The 2010 voter turnout is based on the percentage of registered voters who cast ballots in the special Senate election. The vote percentages for Barack Obama in 2008 and Martha Coakley in 2010 are based on their share of the total vote in each race.

Sources: America Votes (CQ Press) for the 2008 presidential returns; for nearly complete, but unofficial results and voter turnout figures for the 2010 special Senate election.

As for Brown, he has been instantly enshrined in the small pantheon of Massachusetts Republican stars – joining Ronald Reagan, the last Republican to carry the state in a presidential election (1980 and 1984) and Mitt Romney, the last GOP candidate to win a gubernatorial election in Massachusetts (in 2002). All three mined the state’s large block of independent voters and made inroads into the Democratic working class – a feat not accomplished that often by Republican candidates in the Bay State.

At the national level, Brown is the latest GOP “man of the hour,” joining newly inaugurated governors Bob McDonnell of Virginia and Chris Christie of New Jersey as models of how to win election as a Republican in problematic or hostile terrain.

Each had their own persona – McDonnell as a competent problem solver, Christie as a foe of public corruption, and Brown as a truck-driving populist in touch with voter anger in a way that his Democratic opponent was not.

All three Republicans were successfully able to harvest public dissatisfaction with Democratic government at both the state and national levels, a target made easier by the current economic unease. And now all three have provided a blueprint as to how other Republicans might win in November.

Chart 3. Shades of Reagan, Romney in Brown Victory

Major Republican statewide victories in Massachusetts have been few and far between over the last quarter century. The GOP has not won a gubernatorial election in the Bay State since 2002, a presidential race since 1984 and a Senate contest since 1972 – that is until Scott Brown’s special election victory this month.

Following is a comparison of the vote percentage for the last three Republican winners for each office based on a sampling of results from Massachusetts’ cities and towns that were picked to illustrate various demographic groupings. “(1)” indicates which of the three Republican winners – Ronald Reagan in the 1984 presidential race, Mitt Romney in the 2002 gubernatorial contest, and Brown in this year’s special Senate election – drew the highest share of the total vote. Communities that were won by the Republican candidate over their Democratic rival are indicated in bold.

Democrat Barack Obama carried all of the cities and towns listed below in the 2008 presidential election, with his percentage of the total vote indicated in parentheses.

Note: The vote percentage for each Republican winner is based on their share of the total vote. Hyannis Port is a part of the town of Barnstable. The non-white share of the population is based on the 2000 census. Of the cities and towns listed above, Boston and Brockton are also more than one-third non-white.

Sources: America Votes (CQ Press) for 1984 and 2008 presidential and 2002 gubernatorial returns; for nearly complete, but unofficial results for the 2010 special Senate election.