Big money creates at least two problems in politics.

First, to get contributions, a candidate might sell out to those who contribute directly to the candidate or to a super PAC friendly to that candidate. Second, one candidate might spend so much as to drown out the speech of other candidates. Both these risks are on display in the 2020 presidential campaign.

Last month, former Vice President Joe Biden announced he was changing his position on accepting help from super PACs because of what he expected President Donald Trump would spend against him.

Super PACs support an individual candidate, though they cannot give directly to the candidate. Federal law limits how much an individual (or a union or corporation) can give to a candidate, but not how much an individual can spend on the individual’s own to support a candidate. The Supreme Court made that rule in two decisions in 1976 and 2010.

A super PAC serves a candidate’s interest without officially coordinating with the candidate. For that reason, Biden technically could not have stopped a super PAC from forming; but everyone in politics knows whether a candidate wants a super PAC or not, and every candidate knows who contributed to a super PAC.

Biden signaled that he wanted a super PAC. Four days later, “Unite the Country” was formed, a super PAC run by a former Biden campaign employee. It can spend to help Biden without limit.

Some super PACs are driven by issues, not by specific candidates. They, too, can receive contributions and spend without limit. Sen. Elizabeth Warren’s campaign treasurer is a generous past donor to several such super PACs supporting liberal causes. He and his wife gave close to a million dollars to liberal super PACs in the last off-year election alone. These super PACs can be expected to spend to support Warren, since her position on issues aligns with theirs.

Technically, Warren can’t stop them from doing so. She maintains that she has encouraged no super PAC devoted solely to her candidacy. The difference between a super PAC such as Biden has encouraged and liberal issue super PACs to which Warren’s treasurer has contributed in the past, and from which Warren can expect to benefit in the future, is hard to discern.

Then there is former New York City Mayor Michael Bloomberg.

Earlier this year, while considering the decision he has now made to enter the presidential race, he announced he’d pay for a presidential run entirely from his own money. Federal law permits that. Bloomberg is worth $55 billion. Bloomberg paid for his three successful campaigns for mayor from his own money, noting that voters seemed to like it, because he was beholden to no one for campaign contributions.

As a candidate, Trump made the same pledge, with the same asserted advantage of being beholden to no one (though he quickly began to accept donations, and has ever since).

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California is indeed a cautionary tale for the nation Perhaps Bloomberg, unlike Trump, will keep his pledge, and that might reassure voters he can’t be bought. There is, however, the second problem with big money in politics: drowning out the voices of others. Bloomberg has just announced that he will spend $100 million on political ads in four states, all attacking Trump. For comparison, that sum is more than the total cash on hand of the top five Democratic presidential candidates, combined.

Every Democratic presidential candidate supports overturning Citizens United, the 2010 US Supreme Court ruling that allowed treating corporations as individuals regarding political spending. However, that is not the root of the problem. The original “money is speech” Supreme Court opinion was Buckley v. Valeo, in 1976. So long as government doesn’t control speech content, we should be free to limit how much money can be spent in campaigns — whether by super PACs or individuals.

Tom Campbell is a professor of law and of economics at Chapman University. He served five terms in Congress and two years in the California state Senate. He left the Republican Party in 2016 to help form the Common Sense Party of California, of which he is now the interim chairman.