This question is related to this answer:
To make a tactical vote, you need an estimate how much votes each candidate is probably going to get. Only then, looking at the numbers, you can decide that it will be tactical to vote Y instead of X -- because X has almost no chance to be elected, and although you would prefer X to Y, you also prefer Y to Z.
Now, how do you get these estimates? Most people get them from the media.
And this is the problem: if you own the media, you can manipulate the election estimates, which lets you indirectly manipulate the tactical votes of citizens. Such a manipulation can easily become a self-fulfilling prophecy.
Typically, to estimate how many votes each candidate is probably going to get, opinion polls are used. This seems to be problematic in many countries as indicated in several articles such as this, this or this one:
(...) opinion polling might be much worse than inaccurate. It's easy to imagine that the polls themselves affect the outcome of the elections they're supposed to predict. Voters may be inclined to jump on the bandwagon of a candidate who appears to be cruising to victory. Or they may stay home if they think their favorite is either out of the running or coasting to an easy win. Many believe that ubiquitous horse-race coverage pushes second-tier candidates out of the picture
> A 2012 international study conducted by the University of Hong Kong > received replies from 83 countries when asked whether they operated > any blackout period for polls during election campaigns. (...) many > mature democracies find no problem with restricting pre-election > polls.
Question: Is there a democratic country that bans pre-election polls for a relatively long period before the actual elections?
- Democratic country - any country marked as Full democracy or "Democracy" in this article
- Long period before the actual elections - at least two weeks