Six summers ago, Joe Lieberman stood before the Democratic National Convention and said in exultation, "Is America a great country or what?" In that moment of his nomination as vice president, and for most of the campaign to follow, the public fascination with Lieberman turned largely on his groundbreaking role as the first Jew ever placed on a major party's presidential ticket. Time magazine put Lieberman on a cover headlined with the single word "Chutzpah." Understandable as it was, the fixation on Lieberman's Jewish identity obscured some other extremely relevant factors in his selection. Like the outgoing Democratic president Bill Clinton and the two-term vice president then running for the White House, Al Gore, Lieberman embodied the centrist wing of the party. As a senator from Connecticut, he had voted in favor of the Persian Gulf War in 1991. During the Monica Lewinsky scandal, he had chastised the sexually wayward Clinton from the floor of the Senate. His private life as an observant Orthodox Jew offered an implicit rejoinder to the Republican attempt to make piety a strictly partisan trait. Except for a dubious vote count in Florida, which then was upheld by a politically divided Supreme Court, Lieberman might well be a second-term vice president right now. Instead he is a three-term incumbent facing a serious challenge in Connecticut's primary election on August 8, and facing it, paradoxically enough, on the basis of the kind of moderate views that so recommended him to Democratic and independent voters in 2000. Lieberman's fate in this campaign may not matter very much to American Jewry - there are dozens of other Jews in Congress, some from such overwhelmingly gentile states as Wisconsin, Minnesota, and Oregon - but it matters greatly to the prospects of his party as a viable force in any national race. THE IRAQ invasion and the bungled occupation have changed many things in American politics, and one of them is the vitality of Clintonian centrism, a third way between stridently conservative Republicans and diehard liberal Democrats. The only issue of any consequence in Lieberman's primary campaign against Ned Lamont, a wealthy businessman who has never held elected office above the municipal level, is the senator's support for the war. The war has become the sole criteria of Democratic legitimacy, at least among the liberal voters who make up the party's activist wing and often the main share of primary-election voters. Their impact has been magnified even more by the emergence of the left-wing blogosphere and Internet-based advocacy groups such as MoveOn.org. Like other centrist Democrats, Hillary Clinton among them, Lieberman has struggled to separate his position on the Iraq War from the appearance of being a lackey of George W. Bush. Indeed, one of Lamont's television ads shows footage of Bush making speeches - but with sound bites of Lieberman. Early in their sole campaign debate, held last week, Lamont declared, "Senator Lieberman, if you won't challenge President Bush on his failed agenda, I will." Nobody need pity Joe Lieberman for being in this kind of nasty race. He played his rhetorical cards in the debate, quoting President Kennedy as the archetypal liberal hawk yet also repeatedly using the dismissive refrain that Ronald Reagan had levied to such devastating effect against Jimmy Carter in 1980: "There you go again." More substantively, Lieberman pointed out that his voting record has followed the Democratic line on most issues and earned him endorsements from labor, environmental, and gay-rights groups, all mainstays of the Democratic coalition. As hard as it is to defend the present fiasco in Iraq, he did not duck or dodge, saying this: "My position on Iraq has been clear. And I believe it was the right thing for us to overthrow Saddam Hussein. I have been critical of the things that the administration did after that. But the fact is, we're there now. And we have a choice. And that choice is between helping the Iraqis achieve a free and independent Iraq or abandoning them and letting the terrorists take over. The latter choice is one we cannot make. And I have leveled with people about it and asked them to respect me for having the guts to take an unpopular political position." WHETHER THOSE guts get rewarded on primary day remains to be seen. Several polls have shown the race tightening, with Lamont pulling with 10 or 15 points of Lieberman among prospective voters. In a typical primary, when as little as 10 percent of registered voters may even bother to turn out, a passionate, single-issue protest campaign of Lamont's sort can score well. Preparing for the worst, Lieberman has announced that if he loses in the primary, he will seek a ballot line in the November general election as an independent. The larger issue here, though, is neither Lieberman nor the Iraq war. It is the condition of the Democratic Party. The Lieberman-Lamont race serves as merely one especially visible and dramatic front in a struggle over the direction of the party. The only Democrats to win the presidency in the last 38 years, as has been frequently observed, are two Southern centrists who were steeped in religion, Bill Clinton and Jimmy Carter. Primarily because of its atrophy in the South, the Democratic Party remains the minority in both houses of Congress, holding just 44 of 100 seats in the Senate and 201 of 435 in the House of Representatives. Like Hillary Clinton and the Illinois Senator Barack Obama, as well as Senate candidates James Webb in Virginia and Robert Casey, Jr., in Pennsylvania, Lieberman represents a sector of the party that recognizes the need to capture socially conservative, fiscally liberal voters rather than losing them to a Republican Party highly skilled in playing the family-values and patriotism cards. The Democrats counted on Bush's incompetence to win them the 2004 election and they were wrong. Howard Dean, the chairman of the Democratic National Committee, ran his own campaign for the party's presidential nomination in 2004 on an antiwar platform. Yet he also spoke insistently of the need to appeal to Southern guys driving pick-up trucks. Because of one intemperate turn of phrase, in which Dean seemed to comment approvingly of Confederate flag decals, he got mostly ridicule for what was actually a smart observation. In the last few months, Dean has called for the Democrats to become a 50-state party once again, spending money on field operations even in the South, Great Plains, and Mountain West, sections of the country that the party has increasingly ignored in the past decade. Dean's initiative brought him into confrontation with Rahm Emanuel, an Illinois Congressman who chairs the Home Congressional Campaign Committee, a major vessel for raising and distributing election money. Strangely for a product of the Clinton Administration, Emanuel has argued for what is essentially the liberal wing's strategy: Win on both coasts and in the industrial Midwest. Win with the activist base. The problem with this design, as both 2000 and 2004 showed, is that the narrowest of losses in even one essential state, Florida in the case of Al Gore and Ohio with John Kerry, means national defeat and continued degradation as the minority party. MORE THAN once in the recent past, the Democrats have fallen into civil war between pragmatists and purists. Harry Truman nearly lost the presidential election in 1948 because Henry Wallace's Progressive Party siphoned off millions of votes on the left. Eugene McCarthy and his followers recoiled from supporting Hubert Humphrey for president in 1968 because they viewed Humphrey, Lyndon Johnson's vice president, as complicit in the Vietnam War. The result, of course, was the election of Richard Nixon and all that entailed. Florida notwithstanding, Al Gore probably would have won the presidency in 2000 had Ralph Nader not mounted his Green Party candidacy. If the Iraq War is going to be the latest deal-breaker for Democrats, then one can expect similar futility come Election Day. The anti-war cause can rally the faithful, but it cannot make the overarching reality of global struggle against militant Islam conveniently disappear. In fact, this pacifism probably overlaps a good deal with the strain of anti-immigrant sentiment loose in America, those two positions coalescing into a kind of populist isolationism. Joe Lieberman had his moment in 2000 as the emblem of any easier virtue, the cover boy for American tolerance. This time, as importantly, he stands for the sad reality that Iraq offers only two choices, both bad, leaving or staying. To punish Lieberman at the polls for making one of them, and to drive the Democratic Party toward the margins, is to say to wonder if America is a stupid country or what. The writer, a professor of journalism at Columbia University, is the author most recently of Letters To A Young Journalist.