As most know, Trump has been making a significant deal out of the Clinton email issue, with a resurgence on the topic occurring recently due to certain comments from the FBI investigator.
Is there any historical example of a similar situation to this, in which a major candidate (not necessarily presidential, or even American) has been accused by some of possible breaches of some law or governmental policy, and the opposing major candidate has used it as a significant line of attack in their campaign? And if so, was this found to be beneficial or detrimental to their campaign?
Barring such historical evidence, is there any current evidence, from polls or otherwise, indicating whether this approach is an effective one?
Please note that I am not seeking opinions on whether the issue is a valid one, or whether Clinton is guilty, or whether Trump is being hypocritical. I'm asking whether the approach is, on the whole, politically savvy or suicidal.
My own instinct, in the absence of evidence, is that those who are on the fence aren't likely to choose to vote for Trump due to this, and thus there are no real benefits - that Trump is effectively "preaching to the choir", and thus potentially squandering an opportunity to get fresh attention from those who are truly on the fence. Is my instinct justified?
EDIT: As so many people seem to be failing to understand what is being asked, here, let me explain it again: I want to know, ultimately, whether Trump's decision to focus on this particular topic is beneficial or detrimental to his campaign - NOT whether people deserve to know about it, NOT whether the topic is legitimate or fabricated, and NOT whether it is "right" to focus on it.
In the shortest way of putting it: Is this focus having a positive or negative impact on Trump's chances of winning?
And to be clear, I don't want vague argument about the impact from a partisan perspective. Think of it this way - if, 500 years from now, some political historian were looking back at this election, had all the data and a detail-cleansed version of the series of events (with no knowledge about policy positions or party alignment), and had to determine whether each of Trump's campaign decisions were beneficial or detrimental, would such a historian determine this particular campaign decision to be good or bad for his campaign?
EDIT: OK, let's try framing it in yet another way:
There are four possible ways that the Trump campaign can react to the announcement by Comey and the ensuing discussion, etc...
- Attack Hillary Clinton, make as much noise about it as reasonably possible, thus potentially drawing more attention to the issue in the hopes of weakening the Clinton campaign.
- Defend Hillary Clinton, assert that the issue that should concern voters is ability to run the country, and thus look like a "positive campaign" and a "good guy" for defending her.
- Go quiet, and let the media focus on Clinton, removing any chance of any sort of gaffe or counterargument, thereby allowing the "attack" to continue without getting any "mud" on themselves.
- Pivot entirely to another topic and treat this as nothing but a distraction, thereby effectively gaining some of the benefit from each of the first three options.
Each of these has benefits and drawbacks. What I am asking is, from the perspective of political science, is the decision made by the Trump campaign to go for option 1 (a) a net positive, and (b) the best option? Surely this is a topic that has been studied extensively by experts in the general case (not specific to Trump)?