So, you can agitate and advocate and campaign for a candidate (or cause) that you believe is pro-liberty, but even if he really is... no, especially if he really is, he will not win. (This is assuming against all evidence that the system isn't rigged to make certain he doesn't win.) The voters are not ready yet. They still care more about what some collectivist puppetician is promising to steal from someone else and give to them. Or who some parasitical politician is promising to "protect" them from. And chances are if he really does win after all your support, he'll betray you and reject liberty once he gets into office.
But, maybe your political activism will get some people to consider the idea of real liberty. Stranger things have happened. But then you have divided your time and effort. I simply choose to put almost all my efforts at this time into making the ground fertile for liberty to take root. I am trying to pave the way by making people ready for liberty so that if political action is helpful to the cause of liberty you'll someday have a receptive audience. And if it isn't helpful, we haven't put all our eggs in one basket.
You do what you think will help and I'll do the same.