Minnesota Roman Catholics will receive a letter this week from the state's bishops, urging them to donate money for television ads asking voters to say yes to a constitutional amendment to ban same-sex marriage.

For many of the more than 400,000 Catholic households expected to get the letter, it marks the first time they've been asked by church leadership to make a financial donation to Minnesota for Marriage, the chief group campaigning for passage of the marriage amendment Nov. 6.

The call for money comes in the wake of the release last week of two commercials by the main group opposing the amendment -- one of which takes issue with the Catholic Church's stance on gay marriage.

In trying to reach every Catholic household in Minnesota, the mailing is "unusual" compared to Catholics' roles in marriage amendment campaigns in other states, said John Green, a political science professor at the University of Akron (Ohio), who studies politics and religion.

"I can't think of anything as direct and as explicit," Green said. "I'm not saying there's anything wrong with it legally, but certainly I'm sure it's very controversial. Catholic leaders have been involved in fundraising. I know of examples where they have reached out to parishioners, but I've never heard of anything quite this comprehensive."

Besides asking Catholics to make contributions, bishops are encouraging them to vote yes on the amendment, according to a letter sent to priests and church administrators last week from Jason Adkins, executive director of Minnesota Catholic Conference, the public policy voice of the Catholic Church in the state.

The mailing "gives Catholics an opportunity to support the passage of the amendment and asks them to send a contribution to where it will be most effective," Adkins' letter states. In an interview Monday, Adkins said the mailing is being coordinated and paid for by his group and will cost close to $100,000.

Church helps finance drive

So far this year, Catholic leadership has been one of the biggest financial backers of pro-amendment forces, directing close to $500,000 in support of it, according to campaign finance records. The Minnesota Catholic Conference said it reported raising $750,000 in 2011. Much of that came in a $650,000 contribution from the Archdiocese of St. Paul and Minneapolis, which tapped its investments to help fund the marriage amendment campaign.

Both Minnesota for Marriage and Minnesotans United for All Families -- the main group trying to defeat the amendment -- will submit their latest financial campaign reports to the state on Tuesday and release them publicly on Wednesday.

Both groups are vying for the crucial Catholic vote in the amendment debate. Like other religious groups weighing in on the marriage amendment, Minnesota Catholics are heavily divided over the measure, which if passed would define marriage as a union between a man and woman.

A Star Tribune Minnesota Poll published Sunday shows Minnesota voters almost evenly split on the question.

The Rev. Grant Stevensen, faith leader for Minnesotans United, said in a statement released Monday that his group has been contacted by thousands of Catholics statewide who are voting no on the amendment.

Many of them are "very concerned and hurt by the amount of money and energy the archdiocese is spending to further this divisive amendment. It's obvious the Catholic church is incredibly divided over this amendment, and a letter like this is only going to further isolate and pull Catholics apart."

In Minnesota United's first released television ad of the campaign season last week, a Catholic couple is shown in a 30-second spot talking about how their views of marriage have changed and they urge voters to defeat the amendment.

In its first scheduled ad Oct. 1, Minnesota for Marriage will make the case for why the group believes the institution of marriage should be preserved as a heterosexual tradition and what's at stake if it is redefined.

Catholics for and against

Diane Haugesag was raised Lutheran but converted to Catholicism in 2008. She was a member of St. Joan of Arc's congregation in Minneapolis until this summer when she decided to leave the church because she disagreed with Catholic leadership over gay marriage and other issues.

"The church has other things it should be spending its money on ... feeding the hungry, providing homes for the homeless," Haugesag said. "Speaking out against war and being an advocate for peace. And I don't see those issues on the forefront at all.

"I see this focus on one issue and it's extremely divisive, which I don't think serves the church no matter what side you're on."

The Rev. George Welzbacher, pastor at St. John of St. Paul, says the Bible supports the idea of marriage between a man and woman, and from the pulpit on Sunday he has encouraged his congregation to vote yes on the amendment.