Just it will, it it makes the lesser of two evils to turn to be actually good, instead of lesser evil.
Ones power in democracy isn't in given ones vote It is in withholding it. Your vote is your hostage and the political party is the hostage negotiator trying to get it from you.
If you give away the hostage before the bargaining even begins, you have no leverage. You are nobody, non-entity. Your opinion and your interests don't matter. Since you always release the hostage, before the negotiating starts.
At some point in comparative lesser of two evils must come the moment of "in absolute measures the evil is too much, even the lesser evil". Withold vote and the egotistical lesser evil, who doesn't want to lose to the greater evil has to listen to your concerns and turn course.
Until the first moment you withhold vote, they can happily slide in behind the greater evil just two microns behind them in the evil slide.