Though this can be a bit tricky, and I've never encountered a fixed
   policy, my experience is that you never lose by letting a politician
   use your institution as a point of civic pride.  Even in NYC, where
   politics can be...complicated, having incumbents and even potential
   challengers come to events (though maybe not at *exactly* the
   same time) seems to be to everyone's benefit.

   Eric Siegel
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