The best way to deal with suspicions like that, either from the Left about the Republicans, or the Right about the Democrats (I still remember plenty of nutball conspiracy theories on Clinton), is to ask this question:

If they DID do things like that, wouldn't they have done it where it would do some real good?

Like WMD in Iraq. If it had all been a conspiracy, or if Bush had known ahead of time there weren't any, you would think they would have planted some "evidence" over there a long time ago. Lord knows it would have been easy enough.

If the Republicans were actually in the business of "knocking off" opponents, there has to be a very long list of names above Johnson's.