Dark Money on the Left: Major Progressive Dark Money Groups

Politically active nonprofit organizations that withhold donor identities operate across the full ideological spectrum of American politics. This page covers the definition and operational structure of progressive dark money groups, how they channel funds into electoral and policy activity, the scenarios in which they are most active, and how they compare to their conservative counterparts. Understanding the left-aligned segment of this ecosystem is essential to a complete picture of undisclosed political spending in the United States, covered in broader context on the dark money authority index.

Definition and scope

Progressive dark money refers to undisclosed political spending conducted through 501(c)(4) social welfare organizations, 501(c)(6) trade associations, and related pass-through entities that align ideologically with the Democratic Party, labor movements, environmental advocacy, or broadly liberal policy agendas. These groups are legally incorporated as nonprofits under the Internal Revenue Code, which does not require them to publicly disclose their donors, provided political activity does not constitute their "primary purpose" under IRS guidelines — a standard the IRS has never quantified with a precise numerical threshold (IRS Publication 557).

The Center for Responsive Politics (now OpenSecrets) has documented that dark money spending is not monopolized by one ideological side. In the 2020 election cycle, left-leaning dark money groups outspent right-leaning groups by a significant margin, with progressive nonprofits accounting for a substantial share of the roughly $1 billion in total dark money reported that cycle (OpenSecrets, 2020 Dark Money Totals).

Three organizational categories define the progressive dark money landscape:

1. Standalone 501(c)(4) social welfare organizations — groups that conduct issue advocacy, voter registration, and electioneering communications without disclosing contributors
2. Donor-advised fund intermediaries — fiscal sponsors and pass-through entities that pool contributions before redistribution to operating groups
3. 501(c)(6) labor-adjacent associations — trade bodies and professional associations engaged in political spending alongside core membership activity

How it works

Progressive dark money groups function through the same structural mechanics that apply to all 501(c)(4) organizations and dark money. A donor — whether an individual, a foundation, or a corporation — contributes to a nonprofit. That nonprofit reports aggregate revenue to the IRS on Form 990 but does not disclose individual donor names on any publicly available filing. The nonprofit then spends on issue ads, independent expenditures routed through affiliated super PACs, voter mobilization programs, or direct grants to other nonprofits.

Several prominent progressive groups have operated through this structure:

• Sixteen Thirty Fund — operated by Arabella Advisors, the Sixteen Thirty Fund functions as a fiscal sponsor for dozens of pop-up campaigns. ProPublica and OpenSecrets have documented that it received over $400 million in a single fiscal year (2018) and redistributed funds to affiliate projects focused on healthcare, climate, and judicial nominations (OpenSecrets profile).
• New Venture Fund — also managed under the Arabella Advisors network, the New Venture Fund reported revenues exceeding $600 million in fiscal year 2019 according to its public Form 990 filing, channeling grants to progressive policy and electoral projects.
• Demand Justice — a project originally housed within the Sixteen Thirty Fund focused specifically on federal judicial nominations, including Supreme Court confirmation campaigns.
• League of Conservation Voters Action Fund — the 501(c)(4) arm of the League of Conservation Voters, active in electoral spending on environmental policy candidates without full donor disclosure.
• America Votes — a coalition-coordinating 501(c)(4) that works across progressive organizations to align voter mobilization efforts.

The Arabella Advisors network, because it uses a single fiscal sponsor structure for multiple projects, is particularly significant as an example of pass-through nonprofits in dark money architecture. Operationally, this allows rapid deployment of funds to issue-specific campaigns without the formation of a new legal entity for each effort.

Common scenarios

Progressive dark money is most visibly deployed in 4 recurring contexts:

1. Judicial confirmation battles — Demand Justice and allied groups spent heavily during the confirmation processes for Justices Kavanaugh and Barrett, running digital and broadcast advertising campaigns. The mechanics of this spending are detailed further at dark money in Supreme Court confirmations.
2. Climate and environmental policy — Environmental 501(c)(4)s fund issue advertising tied to specific legislative votes, particularly around clean energy and emissions regulation. See dark money and climate policy for a full treatment.
3. Healthcare legislation — Groups opposing ACA repeal or supporting prescription drug pricing legislation have operated through dark money channels. This scenario is examined at dark money and healthcare policy.
4. State-level ballot measures — Progressive nonprofits fund signature-gathering and campaign advertising for ballot initiatives on minimum wage, cannabis legalization, and reproductive rights, often without disclosing the original funding source under gaps in state dark money disclosure laws.

Decision boundaries

A common analytical error is treating dark money as a uniquely conservative phenomenon. The organizational architecture — 501(c)(4) fiscal sponsorship, donor-advised fund intermediaries, affiliated super PAC pairings — is ideologically neutral. The dark money republican and conservative groups page documents the parallel conservative ecosystem, including the Koch network and Crossroads GPS.

Key distinctions between the progressive and conservative dark money ecosystems involve structural concentration rather than legal mechanism:

Both models operate within the same FEC disclosure rules for dark money framework, meaning neither is required to disclose donor identities at the federal level for independent expenditure activity conducted through nonprofits rather than directly through political committees. Reform proposals affecting both sides are surveyed at dark money disclosure reform proposals.