Let us say that you were in charge of the Ministry for Shenanigans, tasked by the Supreme Leader with interfering with the democratic elections in Freedonia, not to ensure the current Prime Minister of Freedonia remains in power, but to sow dissent amongst its people.
The current Prime Minister of Freedonia is known for saying random nonsense, but is not actually known for having the competence to pull off any of the conspiracies everyone knows he would like to engage in.
If anything, he is so mindbogglingly incompetent that nobody would dare try to involve them in a conspiracy, because everyone knows that if you tried, he would boast about the plan the next morning in the middle of a breakfast TV interview that was supposed to be a fluff-story about cheese exports. Everyone knows this, because during the last election he openly asked you to interfere, and then went on to boast about getting your help, even though you actually didn’t bother that time. The fact you genuinely didn’t help him then is the only reason he has not already been removed from office and inserted into a prison cell.
So, what do you do given that it is absolutely vital that all of your actions are deniable? Remember, the goal is not to get this moron elected, it is to cause civil disorder within Freedonia. To make Freedonia care more about its internal affairs than whatever the Supreme Leader is doing.
You wait for the Prime Minister to say or do something corrupt and stupid. Perhaps he will claim that suicide bombers are plotting to blow themselves up in the polling stations, and therefore all voters must be naked, even though the election is in the middle of November. Perhaps he will make spurious claims about postal voting. Perhaps he will require people to show a voting-specific ID card but only send those cards out to people likely to vote for him.
It doesn’t really matter what nonsense he comes up with, because Freedonia has a constitutional separation of powers that limits the damage the Prime Minister can actually inflict.
What does matter is that he will say these things, and many voters will see this as a threat to their vote and (quite understandably) be very angry. They will organise. They will suggest ways around his schemes. They will think themselves very clever. Broadly, they will also have no idea how anything works.
You will use your fake social media accounts to join in. You will seem real, genuine, pro-democracy. But… the ideas you will be feeding the Freedonian electorate are those which sound good and yet do not work. Ideas like “online voting with blockchain” (you know how easy it is to break into a Freedonian government website) or “posting your vote directly to the $insert_address_here” (oh, but post that goes there never gets read).
Most of the public won’t be able to tell which advice is good and which is bad, so if experts warn against listening to bad advice, the public are still just as likely to do the wrong thing as the right thing.
Either way, an increasing number of people start distrusting the result. When the results come in, they have an excuse ready and waiting for why they lost: not because their politics were unpopular, but because the other lot corrupted the vote.