DURING THEIR MANY years in the minority wilderness, Republicans had an adage they called the 11th Commandment: "Thou shalt not speak ill of thy fellow Republican."
The Grand Old Party wasn't always able to follow that dictum on its way to taking over Washington and state houses in much of the country. But it's good advice for the Democrats to keep in mind as they conclude their battle for the presidential nomination.
Any low blows they land now on their ultimate standard-bearer are likely to haunt him through the general election contest with President Bush. If reclaiming the White House is their top priority, the candidates' time now is far better spent sharpening the party's message than sticking it to each other.
So far, this primary season has been energizing and restorative for the Democrats. Once the race really got going last month, the competition among an unusually large field of strong candidates has frequently dominated the national news - often pushing the president off the front page.
Voter turnout in the early primary states reached record highs, and heavy use of the Internet has helped attract first-time donors and volunteers into the process.
To be fair, Mr. Bush deserves much of the credit. The president who promised to be a "uniter not a divider" has been wildly successful at uniting Democrats behind the proposition that he should not be given a second term. At least one-third of Democratic voters say they are not only dissatisfied with the Republican president's service so far, but angry at him. Much of front-runner John Kerry's support appears to be based less on the senator's personal appeal than on voters' strategic calculation that he has the best chance of beating Mr. Bush.
But as Sen. John Edwards and retired Gen. Wesley K. Clark try to parlay their single-state wins in Tuesday's primaries into the string of victories it would now take to stop the Kerry juggernaut - and former Vermont Gov. Howard Dean fights to claim his first success - they should stick to promoting themselves rather than tearing down Mr. Kerry, for their own sake as well as his.
Democratic voters are also signaling this year that they want an upbeat message on which to hang their hopes. Decorated Vietnam veteran Kerry and Mr. Clark are both scoring with a military machismo offset by progressive social policies. Mr. Edwards flashes a dazzling smile and Southern populism. Dr. Dean has junked the scream and invoked the Energizer bunny.
Sunny centrist Sen. Joseph I. Lieberman wasn't able to get his Joe-mo going - even with a laser-like focus on tiny Delaware. Upbeat or not, the No. 2 guy on the Democrats' last ticket is tainted with that loss.
Democrats crave a winner.