.. that an untapped vampire who attempted to block a political action, but failed and was tapped by a Faceless Night, cannot play a Delaying Tactics?
The reason is that Faceless Night says ".. becomes tapped when the action is resolved", which effectively means "before resolving the action". So when the minion is tapped by Faceless Night, he needs to untap (or play a card that allows him to play a reaction card as untapped), if he wants to play Delaying Tactics (or any similar card that is played during the referendum).
On the other hand, if an untapped vampire is attacked using Bum's Rush, and is tapped before resolving the action (the combat) by Faceless Night, he can play Majesty or Earth Meld and is safely untapped after the combat.
Reference: VtES Usenet Newsgroup.