Some of the best-known corporations in the US, including AT&T, Boeing, Delta Air Lines and the Home Depot, collectively poured more than $8m into supporting election deniers running for US House and Senate seats in this month’s midterm elections.

A study by the non-partisan government watchdog organization Accountable.US, based on the latest filings to the Federal Election Commission, reveals the extent to which big corporations were prepared to back Republican nominees despite their open peddling of false claims undermining confidence in democracy. Though many were ultimately unsuccessful in their election bids, the candidates included several prominent advocates of Donald Trump’s lie that the 2020 presidential election had been stolen from him.

At the top of the list of 20 corporations backing election deniers through their political action committees (Pacs) is a familiar name in the world of rightwing agitating – Koch Industries. According to the Accountable.US review, the Koch energy conglomerate spent $771,000 through its Pac on Republican candidates with a track record of casting doubt on elections.

Koch Industries is the second-largest privately owned company in the US. It is notorious for using its largely oil-related profits to push conservative politics in an anti-government, anti-regulatory direction under its owner brothers, Charles Koch and David Koch, the latter of whom died in 2019.

Close behind Koch is the American Crystal Sugar Company Pac, which spent $630,000 supporting election deniers running for federal office; the AT&T Inc Employee Federal Pac, which contributed $579,000; and the Home Depot Inc Pac, which gave $578,000. Lower down on the list comes the media giant Comcast Corporation & NBC Universal Pac, which contributed $365,000; and the Delta Air Lines Pac, which gave $278,000.

The $8m contributed by the top 20 corporations was just a slice of overall corporate giving to election deniers in the 2022 cycle. An earlier analysis by Accountable.US found that, in total, election deniers benefited to the tune of $65m from corporate interests.

The new study suggests that top corporations that chose to use their financial muscle to enhance the chances of election deniers waged a non-too-successful gamble. The Washington Post has chronicled how 244 Republican election deniers ran for congressional seats in the midterms, and, of those, at least 81 were defeated.

Kyle Herrig, president of Accountable.US, said that the fact that election deniers at both the federal and the state level struggled at the polls should make corporations reconsider their strategies. Backing candidates who advanced conspiracy theories harmful to democracy could damage their public reputations.

“Voters’ rejection of numerous election objectors at the polls should send a clear message to corporations that prioritizing political influence over a healthy democracy could threaten their own bottom line,” Herrig said.

The Guardian reached out to several of the top 20 corporate donors for their response. The Home Depot said that its associate-funded Pac supports candidates “on both sides of the aisle who champion pro-business, pro-retail positions that create jobs and economic growth”.

AT&T and Delta did not immediately reply.

The decision to support election-denier candidates stands in contrast with the strong public stance initially taken by several of the corporations in the wake of the 6 January 2021, insurrection at the US Capitol.

Boeing released a statement days after the insurrection in which it said it “strongly condemns the violence, lawlessness and destruction that took place in the US Capitol”. In the 2022 cycle the Boeing Company Pac contributed $418,000 to support Republican candidates who had been vocal in forwarding lies questioning the validity of the 2020 presidential election.

Boeing declined to comment.

Among the individual candidates whose bid for federal office was supported by top corporations was Derrick Van Orden, who won a close race to represent a swing district in Wisconsin with backing from Koch Industries. Van Orden, a former Navy Seal, was inside the Capitol grounds on January 6.

Scott Perry received support from the Kochs, AT&T, Boeing and other corporations in his successful campaign to hold onto his House seat in Pennsylvania. Perry was deeply involved in attempts to block Biden’s victory in 2020, and in the weeks after January 6 sought a presidential pardon from Trump.