There's a walkthrough in the OP for a step by step.Ok. It seems the time was the issue. I finally got the option to end the election.
I was afraid something was bugged, because I had to wipe my saves once, because starting the election event got bugged. After I refused to activate in on first opportunity, it never showed up again.
EDIT: Now the problem I face is that I didn't completed all the events for the campaign, but I can't find anything new. I'm supposed to install a cam in girl's locker room, but I don't seem to get that option. Wheter I go morning or afternoon, there's no prompt.
I have the camera and I talked with Diaz in strip club. I can't find what I'm missing.
EDIT2: Ok. Apparently I should have go to election HQ. That's something I avoided on puprose, because it caused posters to be changed and lower Lauren's score. But now I have the Locker Room Run unlocked.
But to install the spy cam in the girls shower, you need to go to school in the \early\ morning.