Trump isn’t going to be president so no need to “stop” him. But if I assume you aren’t as myopic as your question suggests, then stopping the collusion of Capital via the false choice of the parties of Capital is the long term goal. Limiting our actions to voting, you have very little power, but power that none-the-less should be exercised.

In a first past the post system, only 2 parties at a time can be front-runners. Those parties do not have to be the same for ever and ever. In the history of the US many parties have risen and fallen, and there is no reason the same can’t occur for the Capitalist parties. In fact it is inevitable. The material interests of you (assuming you aren’t a billionaire, or rent-seeking class) are currently not being addressed by either party. So it is your duty to vote for a party who DOES represent your material interests. If you vote either blue or red you are voting against your material interests and mine and 90% of the citizens of the US.