10. The method of claim 5 , further comprising receiving, from the content item provider, data specifying a set of content items that are only eligible for presentation when the user identifier from the search query matches a retargeted identifier from the retargeting set.
11. The method of claim 10 , wherein receiving data specifying the set of content items comprises: receiving data requesting that a particular a copy of a particular advertisement group be copied; and receiving data indicating that the copy of the particular advertisement group be targeted using the retargeting set.