Campaign watchdog group Colorado Ethics Watch has filed a complaint with the Internal Revenue Service requesting an investigation of four non-profit organizations, including Iowa-based American Future Fund (AFF).

The complaint says AFF and three other groups — Coloradans for Economic Growth, Freedom’s Watch, and Western Skies Coalition — have each spent more of their total resources on actions that influence elections in Colorado rather than on social welfare activities, in violation of their federal tax-exempt status.

Each of the four groups is registered with the IRS as a 501(c)(4), a section of federal tax code that exempts them from federal income taxation if they operate primarily to promote social welfare. They also do not have to disclose donors and are not governed by the Federal Election Commission.

Ethics Watch alleges that more than half of the activities engaged in by these groups are “partisan, non-educational activities that provide benefit to various conservative candidates for state and federal public office in violation of statutory requirements for 501(c)(4) organizations.”

“Each of these organizations have paid considerable money to purchase television ads attacking U.S. Senate candidate Mark Udall and candidates running for the state legislature,” said Chantell Taylor, director of Colorado Ethics Watch, in a statement.  “Based on our research, it appears that the organizations are primarily engaged in political activities and need to show where, how and what they are doing to promote the welfare of the community at large.  If they do not, they can and should lose their tax exempt status.”

An Iowa Independent investigation into American Future Fund in August found the group has considerable ties to prominent figures in state Republican politics, including two former executive directors of the Republican Party of Iowa and a prominent donor to state party candidates.

The group’s leadership also includes media consultants who played key roles in the Swift Boat Veterans for Truth ads in 2004 and the Willie Horton ad in 1988, both of which helped defeat Democratic presidential candidates.

In addition to its efforts in Colorado, AFF has been active in competitive Senate races around the country.

Representatives of AFF did not respond to requests for comment.