Soft Money

Soft money is money that is donated to political parties where the purpose is not to promote a specific candidate. Soft money is largely unregulated, and there is no cap on it. Political parties can essentially spend it on whatever they want as long as it fits a generic objective to "increase the vote."

Soft money is often called "nonfederal" contributions. 

Soft money became more prominent after the Federal Election Campaign Act (1974) restricted the amount of hard money individuals, and political action committees could donate. 

Donations to individual candidates are often called hard money. Hard money has firm restrictions and is highly regulated when it comes to how much can be donated, where it can be spent, and on what.

Soft money has no such restrictions. So, to bypass these restrictions, soft money donations became a prominent form of political giving. Soft money is given to the party and not the candidate. The Act says that soft money cannot be used by the party to promote a particular candidate. 

While soft money is donated to political parties, and can't be used to support federal candidates, it can be for 'party building' activities. And the line between party building, and supporting federal candidates can be very thin. 

Since the Federal Election Campaign Act, the amount of soft money campaign parties have received and used has skyrocketed. During the 1992 election, there was less than $100 million in soft money used by political parties, by the 2000 election this amount had reached $750 million.  

In the Bipartisan Campaign Reform Act (BCRA) of 2002 soft money was officially banned. Since the passage of the BCRA, the bill has seen numerous Supreme Court decisions gutting the bill. 

Most recently, a Supreme Court decision in the 2014 case, McCutcheon v. Federal Election Commission, allowed for new forms of soft-money donating which have, according to a report by Politico, resulted in "parties...more aggressively and successfully courting a small number of deep-pocketed donors, giving the wealthy another way to exert their ever-growing influence over politics. And the national parties, which had lost their luster as deep-pocketed donors steered their money to other vehicles, are once again flush with burgeoning amounts of cash whose origins can be difficult to divine."

In some fields, soft money can mean paper currency, as opposed to gold, silver, or some other coined metal.