There’s no better example of the national Democratic difficulty with the war in Iraq than the senatorial re-election campaign of Joseph Lieberman of Connecticut. Elected with 63 percent of the vote in 2000, he is now struggling through a primary against a novice opponent, businessman and war opponent Ned Lamont, and recently announced that he is prepared to run as an independent if he loses the primary next month.

This would, naturally, greatly increase the chance of the two splitting Democratic votes and helping Republican candidate Alan Schlesinger win the general election. But it also does something further though less obvious: It tells Democrats that their party is floundering on an issue for which Republicans are supposed to be vulnerable. And by punishing Sen. Lieberman, it establishes a litmus test within the party, which will result in peeling away still more voters whose feelings about the war are mixed. Some, for instance, may believe the administration has bungled Iraq since before the war and yet not like the pull-out-now option either.

Sen. John Kerry of Massachusetts last month proposed a measure demanding the withdrawal of U.S. troops from Iraq over the next year and got only 12 Democratic supporters. Sen. Carl Levin of Michigan offered a milder nonbinding resolution calling for U.S. troop redeployment to begin by the end of this year and did better, but still ended up losing soundly. This is not a party asserting itself but one taking tentative steps to discover what it thinks.

Maine residents know Sen. Lieberman not only from his presidential runs but also from his work on many issues with Sen. Susan Collins. He is the ranking member on the Homeland Security and Governmental Affairs Committee, which Sen. Collins leads. The two have proposed legislation on intelligence reform, port security, communications interoperability and civil service reforms.

They worked together on the recent Hurricane Katrina report. They have been effective because their party affiliations have mattered less than the work before them. This is hardly an endorsement of Sen. Lieberman’s campaign, but it is a recognition that the war is one issue among many, albeit an especially important one.

If voters believe that the only thing that matters is what a member of Congress thinks about the war, then members of Congress will divide themselves according to their state’s liking and ignore too many other issues. That may end the war faster or it may prolong it; certainly it will make Congress a less effective, more divisive place.