Last Saturday, one supporter of former Vermont Gov. Howard Dean held a placard outside the state's Democratic annual convention that inadvertently said it all.

``Beantown is Dean-town,'' it read.

Big problem. For the convention was at the Tsongas Arena in Lowell, not Boston. And not only did Dean's fans not know where they were (``As far as they're concerned, everything south of Vermont is Boston,'' gibed one delegate), but they were flat-out wrong.

This was John Kerry's day. In the ground war that is a long primary campaign, Kerry won a decisive battle: Once wary and hesitant, the state's Democratic Party has now closed ranks, putting itself firmly behind his candidacy.

Phil Johnston, the party's chair, kicked it off, enthusing about next year's national convention in Boston where, he assured the gathered loyalists, ``We will nominate John Kerry to be the next president of the United States.''

Nikki Tsongas, wife of the late Sen. Paul Tsongas, gave Kerry a heart-felt introduction and the crowd went wild as hundreds of Kerry supporters marched through the aisles chanting and waving banners. Most of the followers of other candidates were kept outside in the rain; in the curious world that is Massachusetts politics, they somehow were unable to secure passes to enter the arena. The best they managed were small desks near the bathrooms at the rear of the hall, where they could hand out literature to those whom nature had called.

And Kerry, sonorous and passionate, put on a good show. That itself was a surprise, for the senator has never been known for his speaking style. His voice is often flat, his manner plodding and he tends to over-intellectualize before an audience, going on and on as if he were teaching a class rather than making a stump speech.

But this was the new Kerry, sounding like he had just graduated first in a Toastmaster course, delivering a stem-winder that had the crowd energized and ready for Republican blood. Unlike any other speaker at the convention, he engaged people. Delegates actually stopped chattering to one another and paid attention.

Smartly, he never spoke about the other Democratic nominees, focusing only on the incumbent president. And the speech, knife-sharp and full of cutting remarks, contained a wealth of pithy putdowns - ``The one American who deserves to be laid off is George W. Bush,'' for example, or ``Country before campaign contributions.'' He slammed the president on domestic issues and the economy (``We should not be opening firehouses in Baghdad and shutting them in New York City'') while at the same time giving him no quarter on foreign policy (``In a place called the Gulf of Tonkin, I worked on aircraft carriers for real'').

By the end, almost the entire crowd was on its feet. The only exceptions were a few dour-faced convention-goers sporting Dean buttons. Even they were clapping.

In retrospect, all of this might not seem like a big deal. After all, it might seem obvious that Massachusetts - like most states - would rally around a native son running for president. And it might also seem obvious that Massachusetts, a tiny state with national ambitions, would be eager to get revenge for the defeats visited upon Paul Tsongas in 1992 and former Gov. Michael Dukakis in 1988.

Six months ago, however, it was not so obvious.

Despite serving for 19 years as one of the state's two U.S. senators, Kerry has always seemed more popular outside the commonwealth than inside. Party regulars don't particularly like him. Unlike the state's senior senator, Ted Kennedy, Kerry is less beloved than he is tolerated.

In fact, when Kerry formed an exploratory committee last December, the immediate reaction was not to join forces with him but to raise questions - about his religion, his wife, his ambitions, his politics, his sincerity and his personality. Local pols hesitated to support him; as recently as last week, it was big news when state Senate President Robert Travaglini made it clear he was backing Kerry's bid.

That, it now seems, is all in the past.

One down, 49 to go.

Of course, Kerry would be mistaken in thinking he has a lock on Massachusetts. The state's Democrats are notoriously fickle. And Johnston, with a reputation of inserting himself into intramural battles, has an uncanny talent for picking the losing side - just ask state Rep. Brian Golden, state Treasurer Tim Cahill, and U.S. Rep. Stephen Lynch, all of whom Johnston worked against.

Still, in the roller-coaster world of a campaign, Saturday was an up day for Kerry. If the Democrats hold on to their fervor, it bodes well for him in next year's New Hampshire primary - a battle that Kerry must win in a state just four miles away from downtown Lowell.

That's Mill City. Not Beantown.

Talk back to Tom Keane at tomkeane@tomkeane.com.