WASHINGTON -- For years, the IRS has done little or nothing to check the rise of overtly political groups that claim a special tax-exempt status in order to funnel secret money into election-related advertising.

But in a sign that the agency may be waking from its slumber, the IRS has sent detailed questionnaires to several Tea Party organizations -- and possibly other political groups -- to determine if they truly qualify for the 501(c)(4) designation intended for groups whose exclusive purpose is to promote social welfare.

Should any group currently calling itself a 501(c)(4) have its designation denied or revoked, tax experts said the consequences could be severe, including fines of 35 percent or more of the money they raised in secret.

And the groups might have to make donors' names public.