Q:

Loshon Hara against public Jewish and non-Jewish figures

Both American and Israeli politics, and of course those of other democracies, can include a lot of personal attacks, both true and untrue, including innuendo about possible adultery, gay or straight, inappropriate behavior privately and/or publicly, influence-peddling, or even speculation as to whether they are "really frum" or just "pretending to be frum."   
To what extent can religious Jews listen to, discuss, or repeat loshon hara about Jewish political candidates or incumbent politicians?   Does it also apply to non-Jewish public figures as well?   Is a person's character ever on the table as a legitimate discussion point when our only source must be second-hand? 
If no right exists for a layperson, is there a halachic basis that would give a Rav or Rosh HaYeshiva an exceptional right -- in their roles as community leaders -- to say loshon hara about political candidates when it is in their community's interest? 
My observation is that rabbis have asserted such a right (even when they later admitted that they had no first-hand knowledge of the truth of the charges, nor had made any investigation), but I can't find any authority that gives it to them. 

A:

If the information is related before three people, then it is considered publicly known, and should one of the three repeat it, he is not guilty of lashon hara , as long as his intent was not to spread it as much as possible.   (Rambam, Hilchos Deos 7:5)

Therefore, one may repeat anything heard from a public news source, and it is not considered lashon hara. 

Personally, I prefer to qualify my remarks with "XYZ news said that..."  , to make it clear that I have no firsthand knowledge of the public figure's alleged misdeeds, and I am only sharing what is already being publicly reported.