I was playing on a custom map i made today (that doesn't crash to desktop! whee!) and was using the exacto money cheat, so I had plenty of well trained soldiers and cops.
At the first election:
1)I order an assassination edict on my opponent, and many of his supporters. After he's assassinated, someone else takes over for him (regardless of how dangerous it obviously is).
2)Repeat (1) until end of election. When the latest opponent is assassinated immediately AFTER I have won the election is where the problem starts.
The game continues to announce new election opponents with "Elections will continue as planned <name> will run against you" going from person to person, despite that none of these people have been assassinated AND no election is in progress.
I guess thats the price I pay for murdering all those people

.
I had been practicing a technique of controlling threats, by checking the leadership ratings of my citizens (including immigrants as they step off the boat, and children). Anyone with an 'Exceptional' leadership rating got an instant assassination edict. The best time to kill someone is when they step off the immigration ship, since then they have no family.
I have a suspicion that ordering assassinations increases your soldiers' respect for you, but I'm not certain of it yet.