Nearly half of all spending during the 2016 election cycle involved political action committees, so on its face, it seems like a sacrifice when Democratic candidates for president say they’re going to refuse corporate donations.

Several, including Sens. Elizabeth Warren of Massachusetts and Cory Booker of New Jersey, have also said they’ll discourage super PACs from advocating on their behalf. Whether they succeed in that, or not, is a more important indicator of whether Democrats can reduce big money’s role in politics.

[Grasswho? Members raised hundreds of thousands, almost none from small donors]

That is popular with the public, according to a recent survey by the University of Maryland’s School of Public Policy, which found that nearly 9 in 10 Americans want to reduce the influence that large campaign contributions have on politics.

Super PACs can collect unlimited contributions from corporations and individuals and spend it on politics, but they cannot coordinate with campaigns. Nor can candidates direct their activities.