MANCHESTER, N.H. ? Barack Obama has become a one-trick pony. But what a trick it is!

The stump speech he has developed in the closing stages of the pre-Christmas campaign is a thing of beauty, a 40-minute oration delivered without notes that is powering his gains in the Iowa caucuses on Jan. 3 and the first primary here in New Hampshire five days later.

Hillary Clinton has nothing to match it. John Edwards has periodic bursts of eloquence. But Obama has reached the point of being able to deliver the speech on demand, and to reach audiences with assured effect. It has become his security blanket.

The speech was introduced at the Jefferson-Jackson dinner in Des Moines more than a month ago, when Obama was still struggling for leverage against Clinton and Edwards in Iowa. It drew rave reviews from that big audience and from Des Moines Register columnist David Yepsen, and Obama knew he had a winner.

He gave it again to the Democratic National Committee at its candidate forum in northern Virginia, and won accolades. So he gave it four more times, when he toured with Oprah Winfrey through Des Moines, Cedar Rapids, Manchester and Columbia, S.C., thrilling about 60,000 people at the four venues.

He has now delivered it in small towns all over Iowa, and here in New Hampshire, he did it six more times in two days last week.

It is a helluva speech. Like some Beethoven symphonies, it starts on a rather calm and even lighthearted note. He hits an early applause line by reminding audiences that next year, “George Bush’s name will not be on the ballot.” Democrats cheer the prospective departure of the man they despise. And then Obama jokes, “Neither will my cousin, Dick Cheney. What an embarrassment to discover he was part of the family.”

He segues to a standard riff about the importance of the coming election, quickly converting it into a pointed attack on Hillary Clinton, although he does not name her. Given the stakes, he says, it is not enough just to change parties or presidents in this election. “We have to change politics. The same old games won’t do; triangulating and trimming won’t do.”

Then Obama pays his respect to Edwards-style populism, ragging on a Washington where health care and energy legislation have been stymied for years by corporate lobbyists – none of whom, he promises, will get the time of day from an Obama administration.

Then he touches the erogenous zones of various Democratic constituencies, promising labor to raise the minimum wage each and every year; promising teachers generous salaries; and promising college students new help in paying tuition.

And finally, comes the peroration, quoting Martin Luther King Jr. on the “fierce urgency of now,” in explaining why he can’t patiently wait his turn to run for president. It’s a bit of a reach because he wants to draw another contrast with Hillary. Unlike others, he says, he has not planned to run for years and he does not regard the presidency as his entitlement.

The closing anecdote is based on an incident at a rally in Greenwood, S.C., where, on a miserable morning, with a meager crowd, a single black woman first revived Obama’s spirit by shouting out encouragement, and then got everyone chanting, responsively, “Fired up!” “Ready to go!”

As he tells the familiar story, Obama segues from a conversational tone to a shout, and explains that the chant has now become his trademark and slogan. So, he tells his listeners, “I’ve got one thing to ask you. Are you FIRED UP? Are you READY TO GO? FIRED UP! READY TO GO!”

And then, as the shouting becomes almost too loud to bear, he adds the five words that capsulize his whole message and sends the voters scrambling back into their winter coats and streaming out the door: “Let’s go change the world,” Obama says. And it sounds as if he means it.

In every audience I have seen, there is a jolt of pure electric energy at those closing words. Tears stain some cheeks – and some people look a little thunderstruck.