An influential group of 28 Republican attorneys general has benefited mightily from at least $9.5m since 2020 from the dark-money Concord Fund, public records reveal.

The Concord Fund, the top donor in 2022 and the two prior years to the Republican Attorneys General Association (Raga), boasts strong links to Federalist Society co-chairman Leonard Leo. Leo helped Donald Trump pick three conservative supreme court justices and now helps spearhead a dark money network that has secured $1.6bn from a single donor.

Since its founding in 1999, Raga has raised and spent tens of millions of dollars to help elect GOP attorneys general – including many who have mounted corporate-friendly lawsuits – but has come under fire from watchdog groups and other critics of the growing role of dark money and special interest industry funding. Many Raga members have waged legal fights against climate change rules and other business regulations.

Other leading donors to Raga in 2022 include an arm of the US Chamber of Commerce, energy giant Koch Industries, and tobacco behemoth Altria, according to the liberal research group the Center for Media and Democracy (CMD).

Raga members have been criticized as a “pay-to-play” operation for filing lawsuits in support of business interests that help fund the attorneys general group, including fossil-fuel companies opposing climate-change rules. Further, Raga sparked strong concerns during Trump’s fight to block Joe Biden from taking office when an affiliate, the Rule of Law Defense Fund, spent $150,000 on robocalls to boost attendance at Trump’s January 6 rally. Those robocalls urged “patriots” to attend the rally and said: “We will march to the Capitol building and call on Congress to stop the stealing.”

Prior to the Trump rally, in late 2020, Texas attorney general Ken Paxton filed an emergency motion with the supreme court backed by 17 Raga attorneys general to overturn Joe Biden’s wins in four states, a legal stratagem that the high court quickly dismissed.

Former Republican Idaho attorney general Jim Jones told the Guardian he was dismayed by Paxton’s legal challenge to the 2020 election, calling it “the high point of irresponsibility. They had no facts and no laws.”

Speaking about Raga members and their focus, Jones said: “They’ve become political operations instead of the people in their states to safeguard the rule of law. They seem to be pandering to rightwing extremist groups to gain office in the first place and then to retain office.”

Jones added that Raga “seems to be focused on cultural war issues and protecting industries that cause detriment to the health of Americans, such as fossil fuels and tobacco.”

Democratic senator Sheldon Whitehouse has also emerged as a leading critic of the increasing amounts of dark money backing Raga and the legal support that many Raga attorneys general have given to fossil fuel companies and other special interests.

“I think the danger here is that [AG] offices that are putatively held for the benefit of the public interest have become law firms for private special interests,” Whitehouse, a former Rhode Island attorney general, told the Guardian.

Whitehouse’s point was underscored in 2021, when Paxton and 19 other state attorneys general sued to block the Environmental Protection Agency from regulating power-plant carbon emissions. The legal battle culminated in a supreme court ruling last year, upholding the EPA’s authority under the Clean Air Act to regulate such emissions, but limiting its scope and pleasing coal company interests.

Similarly, many Raga members have joined another growing legal battleground for fossil fuel interests. Earlier this year, 25 GOP attorneys general, including Paxton, sued the labor department over a new rule that allows retirement plan sponsors more leeway to consider environmental, social and governance matters when making investments. A press release from Paxton’s office in January erroneously claimed that the labor rule favored what he dubbed “woke” investingabove retirement savings.

Besides Paxton, some of Raga’s most active supporters of fossil-fuel interests include attorneys general from South Carolina, Florida, Louisiana and Mississippi, according to a Union of Concerned Scientists report.

Paxton, who was recently impeached by the Texas house on 20 charges including bribery and other misconduct, has received more funding from fossil-fuel interests than any other sector, according to the nonpartisan OpenSecrets. Fossil fuel giants including Koch, ExxonMobil and Chevron since 2002 kicked in over $3.9m to his campaigns.

Critics notwithstanding, Raga’s fundraising operation features wooing of corporate donors at wealthy locales, including Sea Island Georgia, where it is held a “retreat” in Mayand one slated for Pebble Beach, California in August that is billed as a “Victory Fund Golf Retreat”.

In the 2022 election cycle, Raga raised $34.5m, according to CMD. After news broke in early 2021 about how Raga’a affiliate paid for the robocalls, some longtime corporate donors held back funding for a while. Later, most returned to the fold.

Inside Raga, the robocall brouhaha quickly led to the resignation of executive director Adam Piper, who issued a statement condemning violence at the Capitol. Although Raga tried to downplay any other ties to the Trump rally, Paxton was a speaker there.

After Trump left office too, Paxton and 10 other attorneys general signed an amicus brief last September attacking the FBI raid for “ransacking” Trump’s Mar-a-Lago residence to recover a large cache of classified and other documents he retained improperly, as Special Counsel Jack Smith charged in the 37-count indictment of Trump.

Raga’a spending in the last elections on behalf of attorney-general candidates included almost $9m to support those who falsely denied or questioned Trump’s loss to Biden, according to ProPublica.

In an internal move that may have enhanced its ties to the Concord Fund, Peter Bisbee, who ran the Rule of Law Defense Fund that paid for the robocalls and previously worked at the Federalist Society when Leonard Leo served as executive director, was tapped in April 2021 to be Raga’s executive director

The Concord Fund was formerly known as the Judicial Crisis Network, and spent tens of millions during the Trump years to help his three supreme court nominees win Congressional approval. Concord was led by Carrie Severino, who once served as a law clerk to Justice Clarence Thomas.

Concord, a key group in Leo’s sprawling dark-money ecosystem, gave Raga $4m in 2022, or about 15% of its total fundraising for the year. Leo’s dark-money operations have garnered attention for notching $1.6bn in 2022 from Chicago businessman Barre Seid, as the New York Times first disclosed.

Some former federal prosecutors have also voiced concerns about Raga’s large influx of dark money.

“The mix of politics, secret money and attorneys general is always potentially toxic,” Paul Pelletier, former acting chief of the fraud section at Justice, told the Guardian.

“Normalizing such large dark money donations to Raga creates not only an unseemly perception of an attempt to use the levers of attorneys general solely for a political end but worse, may foment corruption.”