A theme of the Republican National Convention this week has been "Country First," a sly suggestion that perhaps certain Democrats do not put their country first. But there's one who embraced this slogan to justify a betrayal. Sen. Joe Lieberman, the 2000 Democratic Party nominee for vice president, came to St. Paul to talk up the candidacy of Sen. John McCain for president because "country matters more than party."

Country should matter more than party and strict adherence to party identity shouldn't preclude sometimes supporting the candidate of a another party or speaking at a rival convention for reasons of friendship.

But loyalty in its many forms is also an important virtue that makes this great country what it is. Some departures from the norm do not rise to the level of betrayal. What Mr. Lieberman did at the Republican convention does.

Mr. Lieberman is a personal friend of Sen. McCain, but so is Sen. Joe Biden, who Barack Obama chose to be his nominee for vice president. It is hard to imagine Mr. Biden ever turning up at a GOP convention. Mr. Lieberman did so with gusto, criticizing Mr. Obama's record and patronizing him by calling him "a gifted and eloquent young man."

To be sure, Mr. Lieberman is only a nominal Democrat these days. He caucuses with the Democrats in the Senate but won election as an Independent two years ago after losing the primary. Nominal or not, there's a history there of support from people who are owed a decent respect. Very few of us are chosen to be on a party's presidential ticket. To turn around and play the turncoat, as Sen. Lieberman did, puts a shameful mark on a once proud career.