Presidential primaries are supposed to produce nominees. They’re not supposed to generate doubts about the integrity of the voting process. Yet the Democratic presidential primary has done just that, and the Republican primary might have had John McCain found himself in a close race. Though both parties are guilty of bad policy, only the Democrats are guilty of bad luck. And only they, as a result, must figure out how to address a very bad situation.

Do-over time!

The party’s problem involves two crucial states, Florida and Michigan, which moved their primaries forward to January in defiance of party leaders’ wishes. The party retaliated by stripping the two states of their delegates. (Republican Party leaders stripped the states of half their delegates.) Florida and Michigan held elections anyway, and Hillary Clinton won both. Neither she nor Barack Obama campaigned in Florida, however, and Obama’s name did not appear on the ballot in Michigan.

The results of both elections are highly suspect, but there are enough delegates at stake to interest both Clinton and Obama. Thus, party, state and campaign leaders are reportedly considering a number of responses, from simply seating the delegates apportioned by a flawed process to splitting them equally between the two candidates, thereby rendering Florida and Michigan meaningless. But no option can address the injustice done to Florida and Michigan voters as well as a new primary.

Problem is, elections are expensive. Florida officials believe a do-over could cost up to $18 million, according to The New York Times. Democratic Party leaders, meanwhile, believe a Michigan redo could cost $10 million. Nobody — surprise, surprise — wants to pick up the tab. But somebody has to, unless the party and the states are willing to disenfranchise millions of voters over a scheduling squabble. They shouldn’t be. Giving voters the stiff-arm is a great way to drive them out of the party.

It seems to us that both the states and the party ought to reach into their piggy banks. Lawmakers in Florida and Michigan moved their primaries knowing that the parties would retaliate. They deserve some of the blame for this mess. But a larger share belongs to major parties, which decided to disenfranchise their own voters in retaliation. That’s both repulsive and stupid. For that reason, the Democratic Party should be willing to chip in for a second Democratic primary.

Even then, of course, the damage done by the botched elections in Florida and Michigan would not be undone completely. Political campaigns change constantly, and it’s impossible to re-create the conditions that prevailed many weeks ago. New primaries could generate very different results than unencumbered primaries held several weeks ago. Nevertheless, it’s the best the states and the party can do, and they should do it. More importantly, neither the Democratic Party nor the Republican Party should make this mistake again.