Updated at 1:22 p.m.

A number of people supporting Mark Andrew have announced the formation of a new committee that will allow them to pour unlimited funds into the mayoral race.

The announcement has the potential to upend what has remained a largely small-dollar campaign, reliant on $500 donations per person. Independent expenditure groups are not bound by the same restrictions.

"Coalition for a Better Minneapolis" is chaired by Bill McCarthy, who heads the Minneapolis Regional Labor Federation. The treasurer is Kendal Killian, an activist who works for the Minnesota Association of Professional Employees. MAPE is not involved, however.

Other groups may be formed on behalf of Betsy Hodges, who has the support of Take Action Minnesota and some other entities experienced in independent expenditures.

In an interview, McCarthy said he expects that independent expenditure spending "would probably run fairly close" to candidate spending by the end of the election. He declined to disclose their major donors or what they would be spending money on.

As for whether the group will be working on messaging that is critical of other candidates, McCarthy would not discuss specifics."Our effort is to get the message out about Mark's leadership," McCarthy said. "And I think that's about as far as I'm willing to go."

Two donors are known: Firefighters union president Mark Lakosky said they have contributed to the effort, while Minneapolis publisher Vance Opperman said he has committed to giving money. Another possibility is the buiding trades union, whose treasurer Dan McConnell said two weeks ago that they had been approached about contributing to such a group.

The full list of donors will be revealed in campaign filings on October 29.

One possible medium for the money is direct mail, which is expensive but can be aimed squarely at targeted Minneapolis residents. Another possibility is television or radio ads. Only Dan Cohen and Jackie Cherryhomes have run ads on television.

An Andrew spokesman did not immediately return a message seeking comment. Campaign finance rules prevent independent expenditure groups from coordinating with campaigns.

The group had the option of filing with the state, which would preclude any meaningful disclosure of donors until 2014. They registered instead with Hennepin County, however, meaning that a donor and spending report will be filed prior to the election.

"Mark Andrew believes in transparency and so do we. Instead of seeking out loopholes in campaign finance law, we will follow the same reporting rules as the campaigns themselves," Killian said in a statement.

Opperman, a longtime Andrew friend and major donor to other DFL campaigns, said that he pushed for the disclosure. He said he is waiting to see more details on other donors, the group's budget and their spending targets before deciding how much to give.

"When [Andrew] first told me he was going to run, I encouraged him to do that," Opperman said. "Primarily because I wanted to see somebody with more than a decade of real entrepreneurship and business experience. And I didn't see that in most of the other candidates, with the possible exception of Jackie [Cherryhomes]."

The Coalition also has a website: KeepMinneapolisGreat.org.