After discussing the laws of brachos for various experiences, I believe it's the Chayei Adam (or the Kitzur Shulchan Aruch? Don't recall off-hand) who concludes: "and a lot of this is basically, if you feel moved to say it, then say it."
If to you, the victory of Candidate A over B feels like really, really good news (akin to oh, a financial windfall, or the birth of a new child), and you feel moved to express that feeling in religious terms, well nu, who's to stop you. (I wouldn't recommend making the bracha really loudly in a crowd of people who were opposed to the candidate, for obvious reasons.) Or if you think the election of Candidate A is terribly tragic, well dayan haemet is there so we can express grief in a religious fashion.
Now we believe that G-d has a plan, so even if you feel an election turned out disastrously, keep an open mind about how things can work out for the best -- but all that's contained within dayan ha'emet -- G-d is the judge of what is truth. The loss of a loved one may work itself out in complicated and even positive ways -- but when we're grieving, we express our grief.
G-d asks Jonah hatov charah lach, which either translates (in an Aramaic sense) as "are you exceedingly that upset?", or (in a Hebrew sense) "is it good to be that upset?" But that's a philosophical question of how you should feel to begin with. If something strikes you as particularly good or bad news, you respond. That's part of being human.