hard money in u.s. political elections refers to
Campaign finance in the United States Federal law restricts how much individuals and organizations may contribute to political campaigns, political parties, and other FEC-regulated organizations. Corporations and unions are banned from donating money directly to candidates ("hard money") or national party committees.[8]
Political action committee Super PACs, officially known as "independent-expenditure only committees", may not make contributions to candidate campaigns or parties, but may engage in unlimited political spending independently of the campaigns. Unlike traditional PACs, they can raise funds from individuals, corporations, unions, and other groups without any legal limit on donation size.[19]