Gloves off for Clinton and Obama?

Hillary Clinton mostly took the high road in the big primaries of Ohio and Texas. She won the way a candidate often does: with appeals to certain demographic groups and by standing out on select issues. As the Democratic contest tightens, however, she and Barack Obama must resist the temptation to win by other means.

And the temptations are huge. The nation has not seen such a competitive and long nominating contest in decades. If Senator Clinton wins the next "big" state, Pennsylvania, on April 22, the race will likely last into the party's August convention.

Even at this point, more states than in past primary seasons have had a say in picking the party's nominee. And more people are engaged in the excitement of choosing a nominee who might shape the country's direction.

Nonetheless the party establishment is nervous. The campaigns could quickly become nasty. Actions that end up giving superdelegates a strong hand or a "redoing" of the Michigan and Florida votes may be seen as unfair. One side might go to court, as happened after the 2000 presidential election.

If the contest ends badly, the party might then decide to rejigger the nominating process for the future to ensure a shorter voting season. It may seek to have a clear winner after only a few states – Iowa, New Hampshire, South Carolina – vote. In other words, make the process less democratic.

That's only one reason why the Clinton and Obama campaigns must not resort to a destructive fight in coming weeks.

To do so would also signal to Americans that politics – even within a party – has become too cutthroat to reflect their values. It would suggest that the polarizing tactics so evident in Washington's day-to-day stalemates are driven less by differences over policy between the parties and more by the desire of politicians of any stripe to win and hold power. That perception would only dampen calls for bipartisanship in solving the nation's problems.

So now is the time to hold fire on dirty tricks, on "going negative," on letting the ends justify the means.

Each candidate has ample qualifications to be the nominee and enough differences in policy and style to campaign on those points alone. The media does an adequate job of pointing out their differences or digging into the hidden corners of their lives.

It's not easy staying clean when the mud flies. "I want to make sure that we stay focused on the issues," Obama said after Tuesday's losses. Clinton, who went into attack mode days before the vote, should recommit her campaign to stay on the high road.

With 12 places left to hold contests, and 611 electable delegates at stake (not counting what happens with Michigan and Florida), Obama is likely to keep his lead in (nonsuper) delegates. He's still behind in the count for superdelegates, but gaining in a behind-the-scenes struggle. And his momentum may have been slowed by Tuesday's results.

For the sake of the party, the current primary process, and the country, they should focus on why each is fit to be president rather than trying to show that the other one isn't.