Labor and advocacy groups are seeking an investigation into whether Wal-Mart Stores Inc. violated federal election laws by soliciting employees for donations to its political-action committee in exchange for charitable contributions to a fund that helps Wal-Mart employees in need.

U.S. companies are banned under federal election law from giving money directly to political-action committees. Corporations can use their own funds to administer PACs but are prohibited from compensating contributors for their donations.

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