Washington ? Sen. Joe Lieberman of Connecticut and civil rights activist Al Sharpton — the two latest entrants in the Democratic presidential field — are, in many respects, the yin and yang of the competition.

Lieberman has won three elections to the state Senate, two elections as state attorney general and three elections to the U.S. Senate, to say nothing of being No. 2 man on a national ticket that won more popular votes than the current president and vice president. He is the best-known of the Democratic contenders.

Sharpton, by contrast, has never won an election for anything, and most observers think him a purely symbolic candidate.

The two are also at opposite ends of the Democratic ideological spectrum, with Lieberman running as a pro-business Democrat and Sharpton describing himself as an advocate for the down-and-out.

Yet, in an odd way that neither of them wishes to acknowledge, they face similar challenges and have similar strategies for enhancing their chances.

They are, for one thing, the most urban, ethnic characters in a Democratic field that features such white bread contenders as John Kerry, Howard Dean, Dick Gephardt and John Edwards. Dean and Edwards have won their prior elections in Vermont and North Carolina, both states with substantial farm populations and rural areas. Gephardt and Kerry were first elected from the suburbs of St. Louis and Boston and fit comfortably into the conventional mold of suburban politics.

Sharpton, an African-American, is a product of New York City’s tribal political warfare. Lieberman, an Orthodox Jew, cut his political teeth in New Haven and worked for years in Hartford.

They face a common problem: the absence of the kind of constituencies with which they are most familiar and comfortable in the leadoff delegate-selection contests in Iowa and New Hampshire. Des Moines and Manchester are the “big cities” of those states, but New York City and Hartford, they are not.

How they finesse those opening-round battles is the immediate challenge facing Sharpton and Lieberman. Some of the strategists in the Connecticut senator’s campaign suggest that he may bypass the Iowa caucuses, as Sen. John McCain did in 2000. But that would put heavy pressure on him to win eight days later in New Hampshire, where Dean has been camped for months and where Kerry is well-known, thanks to Boston television.

As for Sharpton, he will find few other blacks in either Iowa or New Hampshire, making South Carolina the first place where he may really try to plant his flag.

And that brings up the other thing they have in common: a one-against-many strategy.

Sharpton would love to be the one black candidate facing five or more white contenders in South Carolina, a state where 40 percent of the Democratic primary voters may be African-Americans. Sharpton may not be the only black; former Sen. Carol Moseley-Braun of Illinois is talking of a candidacy. And his electoral appeal to fellow-blacks is unproved, and may be much smaller than that displayed in his earlier runs by South Carolina-born Jesse Jackson. But to the extent that Sharpton has leverage in the contest, it rests on his ability to solidify the African-American vote against a field of rival white opponents.

Lieberman is counting on a similar fracturing of the vote — but on ideological, not racial or religious lines. He is the designated favorite of the centrist Democratic Leadership Council, representing the most pro-free trade, business-friendly wing of the party. The DLC was home base for Bill Clinton and Al Gore, but its leaders, like Lieberman himself, dissented vocally from the populist “people vs. the powerful” rhetoric Gore adopted in his campaign against Bush.

Variations on populist themes can already be heard in the rhetoric of Gephardt, Edwards, Kerry and Dean — to say nothing of Sharpton. If those five split up support from the party’s union-minority-feminist left, Lieberman could win plurality victories in early contests as the only strongly religious, economically centrist and culturally conservative candidate, without grabbing anywhere near a majority of the vote.

That is exactly how it worked for Jimmy Carter in the big Democratic primary field of 1976. In the Iowa caucuses, Carter finished second to “uncommitted,” but reaped massive publicity by winning a bit less than 28 percent of the delegates. He received an almost identical fraction of the vote in New Hampshire, but led the field and established himself as the favorite for the nomination, as four more liberal rivals divided the bulk of the support.

In the end, Carter triumphed, even though he won a majority of the votes in only eight of the 26 primaries he entered. With an accelerated calendar in 2004, that could happen again — at least that is the hope sustaining the latest candidates to join the Democratic race.