Can a Catholic with a properly formed conscience vote in support of abortion?

[Lapey]

A Catholic would be guilty of formal cooperation in evil, and so unworthy to present himself for holy Communion, if he were to deliberately vote for a candidate precisely because of the candidate's permissive stand on abortion and/or euthanasia. When a Catholic does not share a candidate's stand in favor of abortion and/or euthanasia, but votes for that candidate for other reasons, it is considered remote material cooperation, which can be permitted in the presence of proportionate reasons (emphasis added).

Okay, I keep seeing this quote come up supporting Catholics who vote for a pro-abortion candidate when there is an opposing candidate that is running to limit abortion to only rape, incest, and life of the mother.

Here is the question, what proportionate reasons can there be to make it "okay" to vote for a candidate that supports many intrinsic evils abortion and euthanasia being two? He also supports same sex "marriage", and embryonic stem cell research.

I understand if a catholic, through no fault of their own, chooses with an ill formed conscience, there is no sin. But a Catholic with a fully and properly formed conscience votes for this candidate, even though he does for none of these reasons instead of the other candidate, what are the proportionate reasons that makes this choice morally acceptable?

[Fr. Vincent Serpa]

Dear friend,

Protecting innocent human life is the most sacred of all social justice concerns. No issue can justify supporting the taking of innocent human life. A Catholic with a fully and properly formed conscience will vote according to the teachings of the Catholic Church. If not, then his or her conscience either is not really properly formed—or he or she is arrogantly defying the teaching authority of the Church and sins grievously.

Fr. Vincent Serpa, O.P.