DURHAM, N.H.--Charisma is a tough quality to learn. But after 10 months on the campaign trail, Democratic candidate for president Paul E. Tsongas might finally be catching on.

After taking months of criticism for his substantive but dull manner, Tsongas is adding a little style.

A standing room only crowd of more than 500, far larger than expected, packed an auditorium at the University of New Hampshire here Monday to hear Tsongas deliver a departure from his usual "stump speech." In it, he called for a renewed sense of "purpose in America."

Tsongas appeared to make a concerted effort to replace his familiar substance-over-style approach with a more impassioned and often humorous, self-deprecating technique.

Commenting on the large crowd which spread to both sides of the stage, for example, Tsongas noted, "This is very awkward because in order to be heard I have to speak out of both sides of my mouth."

And to demonstrate that all people face adversity in life, he described his childhood.

"I lived in a very disadvantaged home," Tsongas said. "Both my parents were republicans."

Paul Tsongas is not a completely changed man, however. There were moments--such as when he coughed directly into the microphone and took excruciatingly long pauses in his speech--when Tsongas seemed to lack the polish of an ordinary presidential candidate.

Ironically, that roughness around the edges, coupled with his clear stands on the issues, seems to be a large part of Tsongas's appeal.

As of today, Tsongas is vying with Arkansas Gov. Bill Clinton for the top spot in New Hampshire polls. With one of the most organized campaigns in the state, Tsongas could easily win the primary, now less than three weeks away.

While many say the 1988 campaign dwelt too often on the public image of the candidates involved, Tsongas has tried to lead the '92 candidates in focusing on ideas. His Call to Economic Arms, an 86-page position paper, offers the most comprehensive printed analysis of issues by any candidate.

"He comes across as a real guy," said Sean R. Lauer, a graduate student in sociology at UNH. "Paul seems to be the only one who is down toearth and isn't looking to impress anyone," saidJayne Marcucci, a UNH first-year who joinedTsongas's campaign the day before the speech.

That unpresumptuous style of politics has drawnmany to Tsongas, who was the only candidate in therace for several months after he announced hiscandidacy in April of last year.

Nick Valcanas, the owner of Nick DeTini'srestaurant in downtown Nashua, N.H., put a Tsongassign in his window the day before the 50-year-oldformer member of Congress announced.

"This guy had the vision to know that thiscountry had a problem," Valcanas explained.

Valcanas offers customers a tableful of Tsongasliterature, including brochures, bumper stickers,and copies of A Call to Economic Arms. Heencourages the many customers talking politics totake copies of the paper, which Tsongas wrotebefore he announced his candidacy.