The top 40 donors are giving more than ever before. Illustration: Ben Denzer/The Guardian Major changes in US law and industry have shifted the sources of large contributions to political campaigns – and how much they spend The upcoming midterm elections will be the most expensive elections ever conducted in the US. And more of the money is “dark” than ever before, meaning it’s impossible to get a full picture of who is spending gargantuan sums to influence races that could provide a critical check on Donald Trump’s second term.

The elections have also shown how money in politics is being reshaped, with the increasingly powerful role played by big donors from the tech industry as well as the growing concentration of spending among a few powerful individuals and corporations.

The impact of the rise of megadonors such as Tesla founder Elon Musk, and an increase in dark money among the very top donors, on this year’s electoral outcome is hard to quantify.

But signs of massive spending are everywhere. Ad industry tracker AdImpact predicts $11.6bn in ad spending this cycle, surpassing the $11.2bn spent in the 2024 presidential election. OpenSecrets, a nonpartisan research group tracking money in politics, pegs total spending in the midterms as on track to reach $11.9bn.

The top 40 donors are giving more than ever before: $2.4bn by mid-October, seven times the amount the top 40 in 2014 gave, adjusted for inflation, according to a new analysis from the nonpartisan, pro-campaign finance reform institute the Brennan Center for Justice. But the significant difference since then is that those top donors now give more to Republicans, and by a larger differential. In 2014, the top 40 gave to Democrats two to one, but this year the top 40 gave to Republicans three to one over Democrats.

Spending from Super Pacs, which can accept unlimited amounts of money to spend in elections, hit the $2bn mark by the end of September, which is 51% higher than the last midterm cycle, adjusted for inflation, according to the Brennan Center analysis.

the New York Times counted at least $1bn that has already been spent by dark money groups by the end of August. “Dark money” is composed of organizations like 501(c)4 non-profits, which are groups that are not required to disclose their donors at all, since they are not supposed to have political activity as their primary purpose. (Those rules are often flouted in spirit, if not in practice.) This dark money spending is increasingly widespread in even lower-profile races across the country, and during primary contests. The Brennan Center’s recent number crunching estimated that dark money groups account for an unprecedented 29% share of the top 40 donors and that $699m is largely untraceable.

The landmark 2010 supreme court ruling Citizens United changed American campaign finance forever by allowing corporations and labor unions to spend unlimited sums on political expenditures. But rules against Super Pacs working closely with campaigns and candidates meant to counter the risk of corruption inherent in unlimited independent election spending are continually flouted and rarely enforced. Trump himself has repeatedly referred to the Super Pac Maga Inc as being under his personal control and subject to his decision-making, which is against campaign finance law.

Democrats are poised to regain control of the House and possibly the Senate, even as Republicans heavily outspent them, with polls showing minimal results from deluges of attack ads in competitive races. Exact figures for the disparity are hard to pin down, and are changing constantly. For example, on Friday, with only days until the election, the former New York City mayor Michael Bloomberg dropped another $36m for Democratic candidates on top of the $80m he already committed. But best estimates show a steep Republican advantage in Senate race spending, and a narrower one in House races.

The surge in spending is a warning sign for elections ahead, Brennan’s Ian Vandewalker said: “We’ve long had a system of limits and disclosures, but that’s increasingly going away.”Vanderwalker points to trends like new very wealthy industries like AI and cryptocurrency that have burst onto the scene, donating heavily to both parties, “clearly hoping for light or no regulation from the government, which is only going to increase”, and megadonors like Musk whose major spending “looks like a business investment”.

Bought by billionaires Elon Musk’s ideological and personal business interests are well-documented, but other top megadonors fly below the radar. George Soros is one of the rare top 40 individual donors who give primarily to Democrats. Billionaires such as Wall Street’s Jeffrey Yass and the Uihlein family (owners of shipping giant Uline) are longtime Republican mega givers, focused on school choice and traditional ultraconservative causes, respectively. Combined, the two families gave at least $260m in the 2026 cycle.

Other megadonors include AI tycoons Marc Andreessen and Ben Horowitz, whose giving focuses on deregulation, advancing the crypto industry and electing pro-AI candidates. Israeli American businesswoman Miriam Adelson gave $67m this cycle and is known for advocating for far-right pro-Israel policies from the US government and exerting significant influence on Trump’s US-Israel policies.

Musk alone has given $483m so far in the midterms, a figure double what Soros gave to Democrats in 2022. The richest person in the world has been focused on trying to help Republicans keep a Senate majority, particularly in a close Texas race. Musk’s business empire and personal fortunes have been aided by his close relationship with the Republican candidate Ken Paxton.

New rules, new industries A June supreme court decision allowing political parties to spend more in coordination with the candidates they support has helped the GOP inject big money from wealthy donors into small but crucial races, where Democrats enjoyed an advantage from raising more directly from smaller donors. Prior to the ruling, national party committees could only spend from $130,600 to $4,071,800 in coordination with an individual Senate candidate, and from $65,300 to $130,600 in coordination with an individual House candidate.

But the court scrapped those limits. The shift means Republican committees have been able to raise more than $48m, dwarfing the $4m additional Democrats added, furthering the influence of big pocketbooks on smaller races that used to benefit from more grassroots local giving.

The past decade has also seen a major shift in the industries that influence elections with major spending. Labor, favoring Democrats, used to account for 14% of the top 40 midterm donors – now, it doesn’t even rank in the top 40, according to Brennan. Traditional finance interest giving has also declined in influence–from almost half of the top 40 donors in 2014 to only 15% this year.

New industries like crypto and artificial intelligence, and megadonors associated with them, are crowding out those traditional industries, as the scale of the big money gets bigger. Even the real estate industry, a longtime steady bipartisan giver, has seen its contributions relatively dwarfed by this new money.

The share of top donors giving to both parties has vastly increased this year, by more than 100 times the levels seen in 2022 and 2018. Strikingly, that means that in this election cycle, the bipartisan big spenders – largely cryptocurrency, online gambling, AI and pro-Israel interests – gave almost as much to both parties as the top donors giving to only Democrats.

All of this cash has resulted in record amounts of spending, but with unclear results. Some polling shows very little movement in Senate races in Alaska, Georgia, Maine, Michigan, North Carolina, Ohio and Texas before and after a GOP ad blitz this fall.

And all of this money doesn’t even account for growing informal influence campaigns – campaign or Pac payments to online social media political influencers are rarely tracked or disclosed. Campaigns can pay through middlemen companies, and the influencers are not required by law to tell their audiences if they are being paid to support a candidate.

Although it’s unknown how exactly the exorbitant spending affected 2026 votes, the bigger shifts cannot be ignored, says Vanderwalker – and serve as a warning for the 2028 election. It’s easier than ever for politicians to rely on one single megarich donor, he said: “In a democracy, it’s supposed to be one person, one vote, and the more one person can influence, the less egalitarian our system becomes.”