Do letters-to-the-editor campaigns work?

Part of the "silly season" (thanks to Fred Black for that great term) is the bloom of letters to local papers supporting certain candidates.  In some cases, individual expressions seem quite heartfelt, regardless of any larger party or issue contexts.  In some cases, the letters seem pretty much obligatory, as if someone feels the endorsement musn't fail to appear among the other letters -- for example, regarding the Sierra Club endorsements. 

Often it seems, however, that there might be a somewhat more coordinated effort to flood the letters pages with statements endorsing a given candidate -- suggesting he or she may be an underdog but with a significant groundswell of public support. 

There's nothing new about this. We see it in every local election, sometimes with respect to contentious propositions. We also see the same phenomenon in local controversies, particularly when there's "well-funded noise" (to borrow a phrase from another thread) from one side -- as with the example of Horace Williams Airport over the last 15+ years, in support of which letters routinely pour in from pilots all over the country.  Letter-writing campaigns are a standard public relations strategy.

Lately, whoever writes the captions for the Chapel Hill News letters page has had a workout spelling Matt Czajkowski's name repeatedly and correctly, without nearly the same challenge regarding Mark Kleinschmidt or Augustus Cho (although I suppose there's less of a spelling challenge there).  Let me state unequivocally that I'm not necessarily saying that the letters supporting Matt Czajkowski have all been solicited or orchestrated -- OR that there's anything deviously undemocratic about their publication even if they were -- only that there have been a lot of them compared to the numbers for other mayoral candidates.

Organized campaign or individually inspired - either way, the presumptions are that such letters persuade, and the more letters, the better the effect.

The question -- and this is from an inveterate letter-writer (whose letter in the Sunday N&O was edited into near incoherence, which shouldn't have surprised me) -- is whether such letter-writing campaigns work.  Have they worked in the past?  Do they work now, in an era of dwindling newspaper readership?

Short of actually going back to count such letters and running the stats against election results, what is your memory of the effect in previous elections or your sense of how things are going now?