WASHINGTON (AP) The Obama administration has launched a bid to rein in the use of tax-exempt groups for political campaigning.

The effort is an attempt to reduce the role of loosely regulated big-money political outfits like GOP political guru Karl Rove's Crossroads GPS.

The IRS and the Treasury Department say they want to prohibit such groups from using in "candidate-related political activity" like running advertising, registering voters and distributing campaign literature as activities that qualify them to be tax-exempt social welfare organizations.

The agencies say there will be a lengthy comment period before any regulations will be finalized. That means that groups like Crossroads and liberal counterparts like Priorities USA will be able to collect millions of dollars from anonymous donors ahead of next year's campaign.