Teams Clinton and Obama agreed this week to move on from their racially loaded fight over the comparative historical import of Martin Luther King Jr. and Lyndon Johnson. But the dustup will hardly be the last in which the politics of personal identity hold sway in 2008.

From race and nationality to gender and sexuality, identity politics will be more overt parts of the 2008 elections than we have seen in generations.

That’s a reality the Democratic Party doesn’t likely cherish. In post-Reagan America, Democrats have proven terribly reluctant to claim their mantle as champions of American plurality. Time and again, the party has chosen to avoid rather than lead the diversity debate.

But unless the Democrats learn that, particularly on such emotional questions, America much prefers a principled stand to a weak-kneed dodge, they’ll turn one of their greatest strengths into a liability.

That’s what they did in 2004. The Democratic establishment cried foul when Republicans loaded state ballots with divisive initiatives on gay rights. Eleven states asked voters to weigh in on same-sex marriage, pumping up the conservative vote and, some argue, costing John Kerry a win—he lost nine of the states, most infamously Ohio.

The problem, however, wasn’t the existence of a debate about gay rights—that’s inevitable as long as gays refuse to cower in the closet—it was national Democrats’ refusal to participate meaningfully in it. At the state level, 94 percent of legislators who voted against the 22 proposed constitutional amendments banning gay marriage won re-election, according to the gay rights group Equality Federation.

The issue will surely return this year, regardless of who each party nominates. Indeed, both of the Democratic front-runners have identifiable records in support of gay rights, if not gay marriage. Nor is it possible to make it through this election without facing the bugaboos of race, gender and nativism, in the form of immigration.

The only question is how the Democrats will deal with these vital issues when they inevitably come up. Will the party articulate a workable vision of a united, modern America? Or, will it triangulate away its convictions?

Choosing to lead rather than dodge the debate about American pluralism may seem politically risky. But continuing to allow Republicans to frame the fight is a certain way to lose both an election and a political soul.

A version of this op-ed was syndicated to daily newspapers around the country via the Progressive Media Project.