Democrats are rejecting corporate PACs. Here's what that means.

"This campaign is about the people of Arizona, not corporate PACs and the mess they've created in Washington," Kelly wrote on his campaign website. "I won't take a dime of corporate PAC money."

But Kelly and his wife, former Arizona congresswoman and shooting survivor Gabby Giffords, actually run a political action committee of their own, and it spent more than $6.4 million in last year's midterms to help candidates who back their mission of preventing gun violence. (Katie Peters, a PAC spokeswoman, said Kelly will step away from the organization to focus on the Senate race and will no longer help set strategy or speak on the PAC's behalf. Officials also said the PAC will not donate to or spend on behalf of his campaign.)

That dichotomy illustrates a growing trend: Democratic candidates, including those running for president in 2020, are denouncing corporate money but still may rely on political action committees with an ideological focus -- along with an expanding pool of energized small-dollar donors -- to help make up the difference.

What are corporate PACs?

Corporate PACs generally refer to a very specific class of fundraising committees: Those affiliated with individual companies that gather together donations from their employees and donate that money directly to candidates. That's different than a PAC funded by a labor union or by donors who unite around single issues, such as gun control or abortion.

Rejecting the donations from PACs aligned with corporations allows candidates to build trust with voters, said Adam Bozzi, communications director of End Citizens United, a group that aims to overhaul the nation's campaign-finance system.

"People are concerned that corporate special interests have too much power in Washington," he said. "This is a way that candidates can take a leadership role and say: 'I'm not taking their money. I'm going to work for you.' "

And the 2018 midterm results indicate there may be few financial downsides for candidates who take that route. Congressional Democrats who rejected corporate money and won their races last year averaged $5.5 million in contributions, according to an analysis by the nonpartisan Center for Responsive Politics.

Corporate PACs and 2020

The no-corporate-PAC pledge already is sweeping through the Democratic presidential primary.

Most of the candidates who have declared their intentions to run for the nomination say they will reject corporate PAC money. Massachusetts Sen. Elizabeth Warren is among those who have gone further: She is promising to accept no money from any kind of PAC or from federal lobbyists. She also wants all candidates to join her in rejecting help from super PACs -- committees that can raise and spend unlimited amounts on behalf of a candidate as long as they don't coordinate their spending with their favored politician.

Most corporate PACs generally don't wade into presidential primaries, so the candidates taking a stand against them are risking very little right now, said Steven Billet, an expert on PAC management who oversees a master's program in legislative affairs at George Washington University.

But the anti-corporate sentiment among Democrats shows they believe it's a winning strategy, he said.

Former Texas congressman Beto O'Rourke, who is weighing a presidential bid, rejected all PAC money in his unsuccessful bid for the US Senate last year and still raised a record-shattering $80 million.

"A lot of people took note," Billet said. "They are saying, 'Jeez. He certainly had enough money to run a competitive race. Maybe this is a place where we can all go.'"