Green Bay Bishop David Ricken is urging parishioners to vote against candidates who support abortion or gay marriage.
Ricken recently sent parishioners a letter saying voting for candidates who support what he calls "intrinsically evil" positions could "put your own soul in jeopardy."
Ricken's letter says the Catholic Church has a responsibility to speak out on moral issues.
His letter goes on to note principals parishioners should keep in mind when voting, including abortion, euthanasia, embryonic stem cell research, human cloning and gay marriage.
The Green Bay Press-Gazette reports the bishop's letter does not specify who should get parishioners' votes.
The Catholic Diocese of Green Bay has 304,000 members in 16 counties.