The IRS has engaged in an active education campain about the rules governing politics and tax-exempt organizaitons, including churches, this year. The basic concept regarding tax-exempt groups, according to the IRS is this:

"...all section 501(c)(3) organizations are absolutely prohibited from directly or indirectly participating in, or intervening in, any political campaign on behalf of (or in opposition to) any candidate for elective public office."

What exactly does the agency mean by "intervention?"  Here is the IRS clarification of the point.

What is Political Campaign Intervention?

Political campaign intervention includes any and all activities that favor or oppose one or more candidates for public office.  The prohibition extends beyond candidate endorsements.  Contributions to political campaign funds or public statements of position (verbal or written) made by or on behalf of an organization in favor of or in opposition to any candidate for public office clearly violate the prohibition on political campaign intervention.   Distributing statements prepared by others that favor or oppose any candidate for public office will also violate the prohibition.   Allowing a candidate to use an organization's assets or facilities will also violate the prohibition if other candidates are not given an equivalent opportunity.   Although section 501(c)(3) organizations may engage in some activities to promote voter registration, encourage voter participation, and provide voter education, they will violate the prohibition on political campaign intervention if they engage in an activity that favors or opposes any candidate for public office.

Bachmann's Democratic opponent, by the way, is Patty Wetterling