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.

Super PACs spent almost $2 billion in the 2016 campaign cycle, about 20 percent of total spending, up from around 11 percent in 2012. The percentage is expected to grow again in 2020.

[This mysterious 2012 super PAC donor may finally be revealed]

During the 2016 election cycle, Priorities USA, the largest Democratic super PAC, spent more than $190 million to support Hillary Clinton.

Corporate PACs, meanwhile, can give $5,000 per election to candidates, an amount easily replaced with strong grassroots fundraising. Individuals may donate up to $2,800 per election. Primary and general elections count separately.

Consider Democrat Beto O’Rourke’s 2018 campaign against Republican Sen. Ted Cruz in Texas. While O’Rourke lost, he was able to raise almost $80 million despite refusing corporate PAC contributions.

[jwp-video n=”1″]