The organization Minnesota for Marriage raised $830,000 last year for its campaign to amend the state constitution and define marriage as a legal union between one man and one woman.
Those funds include a $350,000 donation from the Minnesota Catholic Conference. The conference also raised another $400,000 for its own pro-amendment campaign.
Minnesotans United for All Families, the primary group opposing the amendment, raised $1.2 million in 2011.
Today is the deadline for all Minnesota candidates, political parties and political action committees to submit their 2011 campaign finance reports.
Groups campaigning for and against the marriage amendment on the November ballot are allowed to accept unlimited donations from people, businesses and organizations. Some have already released a detailed list of their donors, but Minnesota for Marriage said its full report will not be available until Wednesday morning.