The sources and amounts of money contributed to the political parties must be fully disclosed. Not so for this type of outside funding. I have done empirical work, with Mike Norton, demonstrating “How Outside Money Makes Governing More Difficult.” The rise of all forms of outside money — not just undisclosed funding — has heightened divisions within each of the parties and increased political fragmentation, which makes putting together effective governing coalitions much more difficult.

From the Axios story:

Why it matters: The hundreds of millions funneled to politically active nonprofits on both sides rival the war chests of national political parties themselves. But the groups operate independently, often run by people whose roles are opaque or unknown entirely and with sources of financing that will likely never be revealed…

Between the lines: Those groups fill many of the key roles of any political infrastructure such as advertising, voter registration and turnout, issue advocacy and data collection.

• But while campaigns and party committees engaged in that work must disclose substantial details about their activities and funding sources, these groups largely operate in the shadows.