Using Paris or Britney's pictures or names in a political ad would seem to fall into the latter category.
But a political ad is NOT a commercial purpose/venture as such, so how do you opine this to fall into that category?
It doesn't matter. The Red Cross is a non-profit organization, but they couldn't use a celebrity's name or face for their ads without their permission.
A celebrity has legal right to their name and face, generally. You need their permission to use them for any purpose. The media gets a pass under the 1st Amendment as they are just reporting the news (no matter how inane, in the case of celebrities).