Sometimes, the members of Europe's elite don't help themselves.
As they gathered back here today, one might have expected to find them a little battered and bruised, blinking into the sunlight and trying to make sense of the kicking they have just received from Eurosceptic voters in many parts of the continent.
Nope. The new members of the European Parliament got together today and agreed to back the arch federalist Jean-Claude Juncker - former Prime Minister of that very big and important European country, Luxembourg - as the new President of the European Commission.
Even the alternative candidates, Martin Schultz of the left and Guy Verhofstadt of the Liberal group, are basically versions of the same thing.
It certainly is true that pro-Europe parties remain in the ascendancy in the parliament and indeed that MEPs are supposed to take a greater role under the Lisbon Treaty in guiding leaders in the appointment of Commission Presidents (ironically, one might say, an attempt to make Europe more democratic).
But it really doesn't look that smart to be choosing this moment to go on with more of the same.
So Mr Cameron's first task at the dinner tonight will be to make sure all three of these men are firmly ruled out of the running.
Given that Francois Hollande of France is in an equally tight spot, perhaps an even tighter one given that he has just lost out to the Front National, the PM will probably succeed.
But it is an example of why the pro-Europe argument is sometimes so hard to make.