A group leading the effort to defeat a proposed constitutional amendment banning same-sex marriage has raised $1.2 million, mostly in the closing months of 2011, according a new campaign finance report.

Minnesotans United for All Families raised the funds last year from more than 5,100 people, with some larger donations coming from wealthy and prominent Minnesotans, including James Pohlad, owner of the Minnesota Twins.

"Thousands of Minnesotans are beginning conversations with friends, family and neighbors about why they need to vote no on this anti-family amendment," said Richard Carlbom, campaign manager for Minnesotans United. "It's not about the money, it's about the conversations."

Minnesotans United's fundraising prowess signals that the ballot question on the marriage amendment could be the most expensive campaign in the state this year. Campaigns must file their state finance reports by Tuesday, but the Star Tribune obtained an early copy of the group's finances.

A leading organization pushing for voters to pass the amendment, Minnesota for Marriage, won't release its reports until the deadline, said Chuck Darrell, a spokesman for the group. It is building a coalition of supporters around the state, including many in the religious community.

"Our fundraising is going well and we will ... raise whatever it takes to get the job done," Darrell said Friday.

Voters will decide the fate of the proposed amendment in November. More than two dozen states have already approved constitutional amendments banning same-sex marriage. Recent polls indicate the margin in Minnesota's vote could be razor thin either way.

State law already prohibits same-sex marriage, but supporters say the amendment is necessary to prevent courts or future legislatures from allowing same-sex couples to wed.

The average contribution to Minnesotans United was about $216, including giving from political groups, and 75 percent of the money came from Minnesotans.

Marriage Equality Minnesota gave the group its largest single donation, $85,000. Marriage Equality Minnesota is a branch of Project 515, a founding organization behind Minnesotans United. The local political-action committee of the Human Rights Campaign -- a national organization promoting civil rights for gays, lesbians and bisexuals -- gave $174,857 through a mix of cash and in-kind assistance.

Among individuals, Marilyn Carlson Nelson, chairwoman of travel giant Carlson Cos., gave $40,000, the largest single donor. Aside from Nelson, more than a dozen gave contributions of $10,000 or more. Among those were Charles Zelle, president and CEO of bus company Jefferson Lines, George Pillsbury and Bruce Dayton, the father of Gov. Mark Dayton.

So far, the financial backbone of Minnesotans United has been a series of small meetings around the state, many in private homes or at churches.

Ellen Eastby, of Fergus Falls, held one of the meetings last fall at her church.

"I really think people need to be valued and their relationships need to be valued," said Eastby, who says she has many gay friends. "Marriage is a huge, positive value in our society, and being able to marry validates the relationship."

Rick Smith, who has given a couple hundred dollars to Minnesotans United and now plans to host a house party for the cause in coming months, never thought of himself as very political. "I think, like a lot of people, I would have just sat on the sidelines," said Smith, 59, a computer security consultant in Hastings.

Smith's daughter is gay and a medical student at Harvard University. She and her partner married in Massachusetts. That his daughter's union would not be recognized in Minnesota caused Smith to join the effort against the marriage amendment.

"There is nothing that can strengthen a family more than letting two people who love each other get married," he said. "I know how hard it is to find a soul mate, and I can't imagine how hard it is that they can't do what is in their hearts."

Baird Helgeson • 651-222-1288