As Father Rutler noted for people who have lesser formation...

"It is incorrect to say that the coming election poses a choice between two evils. For ethical and aesthetic reasons, there may be some bad in certain candidates, but badness consists in doing bad things. Evil is different: it is the deliberate destruction of truth, virtue and holiness.

While one may pragmatically vote for a flawed candidate, one may not vote for anyone who advocates and enables unmitigatedly evil acts, and that includes abortion. “