Pope Benedict XVI Quote

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.

2004 memorandum to Cardinal Theodore E. McCarrick of Washington, D.C.