A Madison-based group that advocates the separation of church and state is taking on the bishop of the Catholic Diocese of Green Bay.
The Freedom From Religion Foundation is challenging the diocese's tax-exempt status after Bishop David Ricken urged parishioners to vote against candidates who support abortion or gay marriage.
An attorney for the Freedom From Religion Foundation has written to the Internal Revenue Service, saying Ricken's letter was an attempt to influence the outcome of the vote.
The IRS's Wisconsin office did not return calls from the Green Bay Press-Gazette.
The diocese issued a statement saying the bishop "wrote his letter out of his love and concern for the people."
The Catholic Diocese of Green Bay is composed of 345,000 Catholics in 16 counties in northeastern Wisconsin.