Paul E. Tsongas was up early the morning following his victory in the New Hampshire primary. The Today Show, Good Morning America and CBS This Morningall wanted him on the airwaves.

And after shaking hands with Bryant Gumbel and Charles Gibson, Tsongas later in the day met a slightly different television personality: David Letterman.

It was fitting for the former senator from Massachusetts that he spend the evening celebrating with Letterman. The two have something in common.

Letterman, despite his status as a cultural icon, continually reverts back to a standard routine of self-deprecating humor. He'll grumble about the paucity of viewers, lack of "babes," etc.

Similarly, Tsongas has spent the last few months reverting to his problems: lack of charisma and similarities with another Greek Democrat from Massachusetts.

Since his very first election to the Lowell City Council, Tsongas has been known for his firm, generally liberal stands on a variety of issues, but never for his style. So the candidate who has been called droopy, boring, bland and uncharismatic has changed his approach--now he makes jokes about being droopy, boring, bland and uncharismatic.

"I intend to make lack of charisma the chic phenomenon of the '90s," Tsongas says.

Setting national trends might not be easy for Tsongas. But playing the role of "uncharismatic man" certainly will.

For one thing, there's his Elmer Fudd-like monotone, punctuated by a slight lisp and a twitch in his upper lip.

Then there's the drooping jowls. He slumps. And his head always seems to be a tad off center. For good reasons, Tsongas seems uncomfortable standing at a podium.

Tsongas' supporters, of course, point to substance of positions and intellectual integrity as attributes far more important than appearance on a podium.

But even when it comes to substance, Tsongas, who refers constantly to his 86-page manifesto A Call to Economic Arms tends to get bogged down in his favorite subject: solving America's economic problems.

This turned out to be a big plus in New Hampshire where voters weary of the recession gave him a victory in the first primary of the 1992 race for the Democratic nomination.

But Tsongas faces what could be a tougher battle against Bill Clinton, his nearest competitor in New Hampshire, when the two vie for votes in the South and Midwest, where citizens may be looking less for economic realities and more for a touch of flair.

Clinton, meanwhile, in his fifth term as governor of Arkansas, is the smoothest of the smooth. While media critics were accusing Tsongas of being bland in the last few months, Clinton drew fire for allegedly sleeping around on his wife.,