To qualify, a candidate must raise sufficient contributions in 20 states and agree to spending limits. In return, they agree to limit their spending to what they get from taxpayers. Candidates who do not take matching funds can spend as much as they want. PACs are the giving arms of special interests and most PAC money goes to incumbents. The ability to shift money between candidate committees means contributors who give to one politician may find their money helping another.
Soft money allows corporations, unions and individuals to get around contribution limits.
Money may be used for party-sponsored issue advertising that can help or damage candidates without explicitly advocating anyone's election or defeat. Issue ads by groups may be thinly disguised endorsements or attacks on candidates, and the sponsors do not have to disclose the source of their contributions or how much they are spending. Lax scrutiny may allow foreign interests to interfere. Presidential spending limits put candidates at a disadvantage against those who have enough money to forgo matching funds, and who therefore can spend freely. Election regulators are so understaffed that they do not investigate problems until long after an election.