Big-money groups backed primarily by billionaire donors are unleashing an unprecedented amount of outside money into key races.

Outside spending has already surpassed $2 billion, smashing the outside spending record set in the 2016 election with two weeks to go before Election Day. That’s according to OpenSecrets’ outside spending tracker, which follows efforts by super PACs, political parties and “dark money” nonprofits, among other groups, to influence elections.

The 2020 election will be the most expensive ever by a large margin, and no election has ever seen anywhere near this amount of outside money. The bulk of that outside spending — $1.7 billion — comes from super PACs and hybrid PACs, groups that can raise and spend unlimited amounts of money independently of campaigns thanks to the 2010 Citizens United Supreme Court ruling.