The stance that politics ought to stop at the water's edge makes sense if and only if the president isn't playing politics with foreign policy.

From The Washington Post:

The Connecticut race has drawn national attention because of what it may say about the president and the politics of Iraq heading into a critical midterm election and the 2008 presidential campaign, as well as what it may reveal about a Democratic Party that often has been at war with itself over foreign policy since the Vietnam era.

Long one of the Democrats' most prominent hawks, Lieberman has found himself at odds with the rank and file in his party, not only for supporting the war so vigorously but also for refusing to engage in the rhetorical combat of a politically charged moment in history. He has warned fellow Democrats that hyper-partisanship on foreign policy issues damages American interests. In recent days, he has noted that he has given the same warnings to Republicans and emphasized that he has not been a blind supporter of Bush on Iraq.

Lieberman's friends and allies have watched this drama play out with differing emotions -- both a sense of sadness that someone they have long respected has been caught in the vise of the Iraq war and a sense of alarm that he either ignored the warning signs or was somehow incapable or unwilling to adjust to them.

"The stance that, for a senator, politics ought to stop at the water's edge makes sense if and only if the president isn't playing politics with foreign policy," said William A. Galston of the Brookings Institution, who has often sided with Lieberman on intraparty battles but disagrees with him on the war.

"But this president and this administration manifestly have played politics with foreign policy, and their chief political adviser has been totally frank about that," he added. "I think it would have been permissible and even advisable for Joe Lieberman to conclude at some point that a bipartisan foreign policy has got to be a two-way street. He really didn't."