If the Democrats are to beat President Bush in 2004, the only way they will do it will be by challenging him from the right on national security issues. Mr. Bush may be vulnerable for his failure to implement the Middle East policy that he laid out in his June speech that emphasized freedom and democratization. If there is a candidate with the credibility to press this point, it is Senator Lieberman, who has a strong record. But Mr. Lieberman’s Middle East tour over the past two weeks has been a disappointment. In Israel, he showed that he misunderstands Al Qaeda’s goals. He claimed, “They are clearly not intending to conquer the United States of America.” Yet that is exactly what they are intending to do. He was also quoted as saying he saw a glimmer of hope in recent talks between Hamas and Yasser Arafat’s Fatah faction of the PLO, a view that seems somewhat rosy-eyed. He spoke — mystifyingly — of the “common values” between America and Saudi Arabia. He announced in an interview with the anti-Semitic organ Arab News that he remained “committed” to the American-Saudi relationship. And he said he had appealed to Prince Abdullah to “find a way to restate his peace plan.” Mr. Lieberman’s reliance on Hamas, Fatah, and the corrupt and oppressive Saudi monarchy undercuts his ability to challenge Mr. Bush. For a presidential hopeful, it’s a false start.