WASHINGTON - The lead group opposing the constitutional amendment that would ban same sex marriage in Minnesota raised $2.56 million since July.

Since their campaign began in late 2011, Minnesotans United for All Families has raised more than $8.2 million from 44,000 contributors, the organization reported Tuesday.

Minnesota for Marriage, the lead group pushing for the same-sex marriage ban, had not released a report late Tuesday, but it had until midnight to file.

Through July, the two main groups on each side of the question had raised nearly $6 million -- with Minnesotans United holding a clear edge.

At the last filing, Minnesota for Marriage had raised about $1.4 million, along with more than $600,000 in support from organizations, including the Minnesota Catholic Conference Marriage Defense and Minnesota Family Council Marriage Protection Fund.

Minnesota's Catholic bishops are sending out fundraising letters this week, calling on parishioners to donate money to help Minnesota for Marriage buy television ads to counter Minnesotans United commercials.

The Star Tribune Minnesota Poll results released this week show that the battle over the amendment on the Nov. 6 ballot is a statistical dead heat, with 49 percent in favor, 47 percent opposed and 4 percent undecided.

Corey Mitchell is a correspondent in the Star Tribune Washington Bureau. Twitter: @CMitchellStrib