New York Attorney General Eric Schneiderman has launched an investigation into donations made to tax-exempt groups, including the U.S. Chamber of Commerce, that may have been illegally funneled into lobbying and political efforts. Unlike so-called super PACs, tax-exempt groups like the Chamber do not need to disclose their donors, despite heavy involvement in political campaigns. On Tuesday, Schneiderman issued a subpoena to executives at a Chamber of Commerce-linked foundation that may have illegally funneled millions of dollars for the Chamber’s political and lobbying activities. The probe marks the first in years to examine tax-exempt groups, which are expected to spend hundreds of millions of dollars this election year on advertisements attacking political candidates.