Can an upbeat political appeal aimed at middle-of-the-road voters overcome a reputation for insufficient personal charisma and open the door to the White House?

Democratic presidential nominee Michael Dukakis clearly thinks so, judging from the ringing address with which he climaxed his party's national convention in Atlanta.Aimed not just at delegates but at a nationwide audience, it was an address that invoked Kennedy-style visions of new frontiers to conquer and emphasized themes of multi-racial justice.

Aware that many Americans have come to view his party as too liberal and too pessimistic about the country's future, Dukakis painted a picture of a country based on economic fairness and opportunity where "each of us counts . . . and we must be knit together as one."

It was not only a decidedly optimistic message, but one that also did much to overcome his reputation for being competent but bland and unexciting.

Unlike both Jimmy Carter and Ronald Reagan, Dukakis constantly described the federal government not as the problem but as the solution.

And with its broad appeal to a wide segment of the political spectrum, his message was underpinned by Dukakis' rare achievement in uniting the Democratic party.

While all that adds up to an impressive impressive performance, it is not without certain problems.

Though his acceptance speech noted that in contrast to the federal deficit he has balanced his state's budget 10 times, the Massachusetts governor neglected to mention that he did so by raising taxes - a point that George Bush can be expected to draw to the nation's attention.

Despite the party's unity, it still isn't clear how big and prominent a role in the Democratic campaign will be played by Jesse Jackson. On this score, Dukakis must walk a narrow line. Too big a role for Jackson would risk his overshadowing Dukakis. Too small a role would risk alienating black voters.

Likewise, despite his three terms as governor and his highly successful campaign for the presidential nomination, polls show that Dukakis is still largely unknown to most Americans. Though his acceptance speech gave the nation its longest and closest collective look at him, it dealt in few specifics.

Certainly Americans are not nearly as familiar with Dukakis as they are with Vice President George Bush, whose career as congressman, Republican national chairman, former CIA director, first U.S. representative to China, and ambassador to the United Nations is a far cry from Dukakis' Massachusetts statehouse experience.

Under the circumstances, a negative campaign won't do. Rather, it should be a campaign marked by much of the same optimism reflected in Dukakis' ringing acceptance speech. What Americans need to hear from the Democratic nominee is not why they should vote against George Bush but why they should vote for Michael Dukakis.