ah, here's the money quote:
Bush, unlike Nixon, Reagan, and Clinton before him, seems genuinely committed to the cause of battlefield success. But he faces a vastly more skeptical public than either of his predecessors did. Nixon, for one, didn't have to contend with opinion polls showing majority support for withdrawal from Vietnam until 1970-1971, by which time he had enshrined withdrawal in official policy. As for Reagan's experience, in the aftermath of the Marine barracks bombing in Beirut, public support for the U.S. intervention increased. Similarly, when 18 Rangers were killed in Mogadishu, NBC, ABC, and CNN polls found that 61, 56, and 55 percent, respectively, favored sending more troops to Somalia. These levels of support evaporated only as it became clear the presidents themselves no longer backed the missions. Today, the situation has reversed itself: The president supports the mission, but no one else does.