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.