Come-From-Behind Win Is Just a Start, Tsongas Says : Front-runner: He comes up from a 2% rating in the polls. Backers worry that news of a strong GOP challenge will detract from his triumph.

When a telephone rang in the middle of his New Hampshire victory speech Tuesday night, Paul E. Tsongas didn’t miss a beat.

“Answer the phone and tell George Bush he can’t concede until November,” Tsongas ad-libbed before a cheering crowd of several hundred at the Razzberries restaurant on the edge of Manchester.

It had been 10 months since the former Massachusetts senator began his long-shot crusade for “economic truth,” and, with his first-place showing in the opening primary, he had passed the first hurdle. He would clear the others as well, Tsongas promised, because of the appeal of his message.

“I’m not running to be Santa Claus, I’m running to be President, and there’s a difference,” he said. “We are a great people. . . . We want to be told the truth.”

Tsongas aimed his remarks at Democratic opponents who wanted, he said, to ignore the difficult truth of the nation’s economic difficulties. And he aimed also at President Bush.

New Hampshire “made him President. . . . He forgot the people of New Hampshire,” Tsongas said. “And tonight, they remembered him.”

In a crowd that seemed to include at least as many journalists as supporters was Tsongas’ aunt, Libby Taterow of Haverhill, Mass. She had gotten up from her sickbed to see her high-achieving nephew, she said.

“This doesn’t surprise me at all,” she said. “Nothing he does surprises me any more.”

Some supporters acknowledged, however, that the joy of Tsongas’ Democratic triumph here might be muted by the Republican primary returns. The unexpectedly strong showing of conservative commentator Patrick J. Buchanan was likely to overshadow Tsongas’ victory and steal some of the press attention his supporters hoped would bring the Tsongas campaign donations and volunteers.

“It’s crummy for us,” one aide said of the news on the GOP side.

And, as television sets flashed different vote tallies, it was unclear whether Tsongas’ margin of victory would be as large as his campaign had hoped. Some in the crowd were clearly confused by Gov. Bill Clinton’s declaration, after 8 p.m. EST, that his vote total made him “the comeback kid.”

At 9:25 p.m. EST, Dennis Kanin, Tsongas’ longtime aide and campaign manager, appeared on the podium to declare, to cheers: “We are going to beat Bill Clinton by at least 11%.”

Still, David Lyman, a Manchester voter, said he was struck by the contrast between the Tsongas crowd’s mood and the mood of the gathering at Buchanan headquarters. “That was electric,” he said. “This seems more subdued.”

A few short weeks before, the mood of the Tsongas campaign had been grim.

By Tsongas’ own estimation, his effort hit rock bottom in January, when a nationwide poll indicated that, after months of campaigning, he had 2% of the Democratic vote. For 2%, he has since lamented, “Why get out of bed?”

When Tsongas opened his Manchester campaign headquarters last May, the turnout was so poor that volunteers ventured onto Elm Street to try to round up extra bodies. Several people they did find in the impoverished downtown neighborhood seemed more interested in the campaign opening’s cheese pizza than in the candidate’s message.