Money in the Shadows: Outside Spending Since Citizens United

The bigger picture: the cost of elections since 2000

Start with the whole pie. The total cost of U.S. federal elections — every dollar spent by candidates, parties, and outside groups combined — was about $3.1 billion in 2000. By 2012 it had roughly doubled to $6.3 billion; by 2024 it reached $14.8 billion. The most expensive cycle on record is still 2020, at $15.1 billion — more than the 2000, 2004, and 2008 presidential cycles put together.

Not all of that growth is Citizens United. Campaigns got more competitive, presidential self-funding rose, and online small-dollar fundraising (ActBlue, WinRed) brought in millions of new donors. And some of the increase is simply inflation: adjusted into constant 2024 dollars, the 2020 cycle ($18.3 billion) was far more expensive than 2024 ($14.8 billion), and the 2000 cycle's $3.1 billion is about $5.6 billion in today's money. Even after stripping inflation out, though, the real cost of elections has roughly tripled since 2000 — and the steepest acceleration lines up with the maturation of the super PAC and outside-money machinery the decision set loose. The rest of this report zooms into that machinery.

(The sawtooth pattern is normal: presidential cycles cost far more than the midterms between them.)

Outside spending exploded

In 2012 — the first presidential election after the decision — outside groups reported $1.25 billion in independent expenditures to the FEC. By 2024 that figure had reached $4.4 billion, more than triple the 2012 total and a record for any cycle. Even the midterms tell the story: $788 million in 2014 grew to $2.3 billion in 2022.

Independent expenditures are the most direct measure of outside money: they are the ads and mailers that expressly support or oppose a candidate, paid for by groups acting independently of the campaigns. The FEC totals below are reported figures, not estimates.

Super PACs now dominate

Super PACs — formally "independent-expenditure-only political committees" — did not exist before 2010. In 2012, their first presidential cycle, they reported $606.8 million in independent expenditures; by 2016 that had grown to $1.1 billion of the $1.6 billion total, and by 2024 to $2.7 billion, roughly six in every ten outside dollars. Add "hybrid" PACs (which keep a separate unlimited account) and the two vehicles created in Citizens United's wake made up nearly $4.1 billion of the $4.4 billion spent in 2024.

The 2026 cycle is under way

The 2026 midterm cycle is in progress, and the early filings follow the pattern. The FEC's most recent interim summary — covering calendar year 2025, the first half of the two-year cycle — shows $56.4 million in independent expenditures already reported, $45.7 million of it (about four in five dollars) from super PACs. For comparison, spending at the same point of the 2024 cycle was the off-year trickle before a flood: the bulk of any cycle's outside money lands in the election year itself.

The 2026-year filings are already bearing that out: FEC records show roughly $394 million in independent expenditures for the cycle as of early July 2026, driven by special elections and primaries. That figure moves daily and is not yet an official summary, so the tables and charts on this site carry the 2026 cycle only as a flagged, partial row — it will graduate to a full-cycle figure when the FEC publishes its 24-month summary in spring 2027.

The money got darker

Not all of that spending is traceable to a donor. "Dark money" refers to spending by groups — typically 501(c)(4) "social welfare" nonprofits and trade associations — that are not required to disclose who funds them.

OpenSecrets tracked $139 million in such spending in 2010 and roughly $180–313 million in the cycles that followed — counting only what non-disclosing groups reported to the FEC. Using a broader method that also captures undisclosed television and digital advertising, OpenSecrets put 2020 dark money at about $1 billion, and the Brennan Center — building on that method — estimated a record $1.9 billion in 2024. By the Brennan Center's accounting, dark money groups have spent at least $4.3 billion on federal elections since Citizens United.

The 2024 money also moved differently. Direct spending reported to the FEC — the only slice the public sees in real time — was just $43 million, under 2.5% of the total. The rest flowed through harder-to-trace channels: about $1.3 billion in contributions to allied super PACs, $315 million in online ads, and $242 million in television. Roughly $1.2 billion of the 2024 total backed Democrats and about $664 million backed Republicans — a partisan tilt that, before 2018, ran the other way.

A note on the numbers: the 2010–2016 figures and the 2020–2024 figures come from two different methodologies and are not directly comparable. The early figures count only spending reported to the FEC by non-disclosing groups; the later figures add undisclosed TV and digital advertising. The jump partly reflects better measurement — but every serious estimate points the same direction: up, and steeply.

Does the money win?

Outside spending is not spread evenly across the map. It pours into a handful of races and ignores the rest. Of the 104 U.S. Senate races held in 2020, 2022 and 2024, fewer than half drew even $1 million of it, and 42 drew almost none at all.

So the interesting question is not whether outside money is large. It is what happens in the races where it shows up. For each candidate we can add the independent expenditures spent supporting them to the independent expenditures spent attacking their opponent — the money spent trying to put them in office — and set it against the result.

The answer is that it buys close to a coin flip. Across the 48 Senate races with at least $1 million of outside money, the candidate with more of it behind them lost 20 times. Among the most expensive races the pattern holds: in the 31 races drawing $25 million or more, the better-funded candidate lost 17 of them. The correlation between a candidate's share of the outside money and their margin of victory is +0.08 — statistically indistinguishable from zero.

Some of the largest sums in modern politics bought nothing. In Georgia in 2020, David Perdue had $171.9 million behind him to Jon Ossoff's $94.1 million, and lost. In North Carolina the same year, Cal Cunningham held a narrow money advantage over Thom Tillis and lost. In 2024, $865.7 million stood behind Kamala Harris to Donald Trump's $793.8 million.

What that does not mean

It would be a mistake to read the chart above as proof that outside money does not work. The causation runs the other way. Money floods a race because it is close, so the races that appear here are, almost by definition, the ones decided by a few points. The safe seats — where a well-funded incumbent faces no serious threat and no super PAC bothers to spend — never enter the sample at all.

What the data does show is narrower, and still striking: once both sides are spending at scale, outspending your opponent buys no reliable advantage. The 2020 and 2022 cycles ran in opposite directions — the better-funded candidate lost three-quarters of the 2020 races and barely one in ten of the 2022 races — which is what a coin flip looks like, not what a purchased outcome looks like.

The money is not buying victory so much as buying presence in the races that decide control of the Senate. That is a different claim, and a more defensible one.

What this is, and isn't

This is the "high points" view: total outside spending, the rise of super PACs, and the growth of undisclosed money, cycle by cycle. It does not yet break down spending by committee, donor, or party — that detail is coming. What the headline numbers already make clear is that the post-Citizens United era moved an enormous and growing share of federal campaign money outside the candidates' own committees, and a large and growing slice of it into the dark.