The New York attorney general announced a a far-reaching draft regulation on Wednesday that would force broad public disclosure of millions of dollars in loosely regulated spending on elections and ballot measures in New York.

The proposal by the attorney general, Eric T. Schneiderman, takes direct aim at tax-exempt organizations that spend heavily on political advertising but have not been required to reveal the donors behind their spending.

The new rules are likely to have a major political impact after they are finalized next spring. Business interests contemplating spending millions to influence next year’s New York City mayoral race would be subject to broader disclosure. The rules would also affect any tax-exempt groups that join expected battles over a proposed constitutional amendment that would expand casino gambling, a top priority of Gov. Andrew M. Cuomo; another constitutional amendment that would alter the state’s redistricting process; and any local ballot measures regarding hydraulic fracturing.

The rules would force disclosure by out-of-state tax-exempt groups, like those that quietly intervened in the battle for the New York State Senate this year, ultimately spending more than a million dollars to back Republican candidates. Many longtime players in New York elections would also have to disclose many donors to their political efforts for the first time.