In reverse, to "get on the [band]wagon" usually means to go along with a new trend. Although the word "fad" has slightly negative connotations, the cheerful cry of "get on the bandwagon!" usually is an optimistic calling.
To put the two together, President Bush, a man who is famous for, among other things, having decided to go "dry" since the day after his 40th birthday, whom one can say hasn't fallen off the wagon, is now calling for Europe to get on the bandwagon of spreading liberty realistically. This is, essentially, the view over at New Sisyphus, whose point is that President Bush is inviting Europeans who may have been aghast at the driving of the bandwagon to hop on nonetheless now that its path is more clear to bystanders.
The MSM, blind as usual, has painted the trip as a “mending fences” mission critical to the President’s success. Nothing could be further from the truth. President Bush’s core message has not changed one whit. What has changed is that the President is now coming off a series of political victories—elections in Kabul, re-election to the Presidency, elections in Iraq, a new movement for peace on his terms in the Israel-Palestine conflict, reform picking up pace in the entire Muslim world—that make it impossible for European governments to continue to view the Bush Administration as an aberration the next “normal” administration will correct. In addition, as the facts on the ground continue to trend Bush’s way, more and more people are beginning to realize that the President’s prescriptions were not wild-eyes “neo-con” fantasy but, rather, a “new realist” view that continues to be vindicated by events.[Cross-posted at Between Worlds]