The donor-funded ProPublica news organization bills itself as an “independent, nonprofit newsroom that produces investigative journalism with moral force… shining a light on abuses of power and betrayals of public trust.”

But conservative activists are calling foul, saying that ProPublica, founded in 2007 by former Wall Street Journal editor Paul Steiger, has a left-wing bias and is funded mainly by left-wing fat cat donors including George Soros — some of whom are not named by the news site.

They say ProPublica’s reporters and editors — some of whom are very well-paid according to tax filings — attack right-leaning figures and organizations, often for a lack of transparency, without actually revealing all the names of their own donors.

Though ProPublica, which listed donations of more than $35 million in 2021 — its most recent disclosure to the IRS — appears to go above and beyond what the IRS requires they disclose about their donors, there is a layer of opacity and fine print that ultimately obscures some of their contributions.

In 2020 and 2021, the organization took in a total of $6.3 million from donors it kept anonymous.

And despite repeated questions about the identity of two donors who appear to have made up nearly a quarter of their donations last year, ProPublica declined to name them to The Post or explain how they donated to the organization.

Some donors opt to donate through Donor Advised Funds which do not require them to disclose who they are. Still, other contributors are listed as “anonymous,” using the New York address of ProPublica, according to federal filings.

The conservative activists, who did not want to be named, were irked most recently by ProPublica’s bombshell April report detailing what they called Supreme Court Justice Clarence Thomas’ “beneficial relationship” with billionaire and Republican mega-donor Harlan Crow — which involved Thomas vacationing with Crow on his yacht and his private jet. Thomas never disclosed these gifts.

“I’m sure in their own minds they are righteous warriors for truth and justice,” said one conservative activist of the nonprofit’s reporters.

“But I know bulls–t when I see it. Among other things, they’re running a very aggressive campaign to target conservative justices of the [Supreme] Court,” the activist added.

“They act all righteous and preening faux-objectivity as if they’re moral giants and we’re knuckle-dragging animals. It’s ridiculous.”

Since it was founded in 2007, ProPublica has won a Pulitzer Prize in 2010 for a story published in The New York Times Magazine and stirred controversy by publishing billionaires’ leaked tax secrets.

According to their 2022 audited financial statement, more than $9.9 million in funding to ProPublica from two donors made up a quarter of the site’s revenues — but the names of those donors were not disclosed.

Some of the site’s ultra-rich donors attended a fundraiser at a luxe Gramercy Park home in Manhattan Monday night thrown by multi-millionaire financier Mark Colodny, who is on ProPublica’s board of directors.

They included Charles Rockefeller, a scion of the Rockefeller dynasty, with his wife Emily Shippee; venture capitalist Joy Marcus, who is a former Condé Nast executive; Sheila Spence, Spotify’s VP of corporate development; and Lawrence Rand, chairman emeritus of the Kekst & Co. PR firm and now a Brown University visiting professor.

One observer noted that they all looked as if they came “straight from Park Avenue, Newport, and Hobe Sound.”

“The sanctimony of ProPublica is a bit much considering they’re bankrolled by left-wing donors yet they dress themselves up as being all about purity and transparency,” one conservative activist told The Post.

“Having a high-end salon in an extremely wealthy financier’s home to fund journalism that has a certain ideology where the funding is not all disclosed and it has a certain ideological bent is pretty hypocritical.”

The longtime Federalist Society leader Leonard Leo, whom ProPublica has called “a key architect of the Supreme Court’s conservative supermajority,” has been the subject of a number of unflattering ProPublica articles.

“ProPublica brands itself as seeking transparency and accountability when here they are having a private dinner with billionaire donors from the New York financial community,” Leo told The Post.

“It begs the question who’s influencing what ProPublica does and what are the special interests that those people represent. They’re taking money from tremendously influential financiers in our country and we have no idea who they are and what they are getting in return.

“I’ve been the subject of ProPublica reporting largely around the subject of anonymous giving within the conservative movement,” Leo added. “So I’m happy to see they’re having dark money dinners because now maybe they’d be in favor of anonymous giving.”

Said one conservative: “ProPublica has built a franchise on reporting on the lack of transparency involving Supreme Court justices. At the same time, ProPublica will not disclose whether its donors have their own conflicts of interest due to business before the Supreme Court.”

ProPublica lists some of its biggest donors on its website — including the Abrams Foundation, the Carnegie Corporation of New York, the Dyson Foundation, and the Commonwealth Fund — and includes tax information for many donors on its site.

The biggest donor to ProPublica in 2021 was Crankstart, the San Francisco-based family foundation of Sequoia Capital founder Michael Moritz, a prominent supporter of former President Barack Obama. The foundation donated $3 million to the nonprofit.

Steve Jobs’ widow, Laurene Powell Jobs, who is worth about $26 billion, gave $2 million via her “social change” investment firm Emerson Collective. Jobs is a well-known Democratic supporter, having given more than $2 million to Democrats in 2020.

At the same time, ProPublica has not shied away from calling out Jobs. She was cited in a 2021 ProPublica piece as among more than half of America’s richest people who avoided paying estate taxes.

The Abrams Foundation, run by David and Amy Abrams, gave ProPublica $1.55 million in 2020. The group also gave Brown University a $1.25 million grant last year so Brown students can work “with partners to collect personal stories that reveal how slavery and colonialism shaped societies across the globe.”

In 2021 George Soros’ Foundation to Promote Open Society gave the news site $175,903, according to ProPublica’s IRS filing.

In 2019, a Soros foundation gave $353,000 to the site. There was no donation from a Soros-affiliated entity in 2020, according to filings.

In response to a query from The Post about the identity of the two donors who contributed a quarter of the site’s revenue last year, a ProPublica spokeswoman emailed a statement:

“The funding you cite was reported publicly on our 2022 audited financial statement. Every year, on our IRS Form 990, we list the donors who contributed $5,000 or more, which provides readers with more transparency about the sources of our funding than the IRS requires of nonprofits. Our 2022 Form 990 will be published this fall, as is our standard practice.”

When asked to provide some transparency about multiple donations that are listed anonymously on their most recent 990 disclosure, ProPublica declined to comment.

According to ProPublica’s 2020 IRS filings, the number of anonymous donations totaled more than $4.9 million. In 2021 it was $1.399 million, totaling $6.3 million over two years.

In December, ProPublica said it would return $1.6 million donated by disgraced FTX crypto king Sam Bankman-Fried.  The site said the funds will be moved to a separate account until a bankruptcy judge or another legal authority says where the money should be returned, Reuters reported.

Timothy M. Andrews, who was an editor at the Wall Street Journal more than 30 years ago and now runs the Philadelphia-based Advertising Specialty Institute, was a guest at Colodny’s fund-raiser earlier this week. He told The Post that editors did not give any hint about future investigations at the event, and considers the outfit squeaky clean.

“I’ve been a donor for a decade and never once have they said anything about what they’re working on in the future,” Andrews told The Post outside the Manhattan soiree Monday night. “If anyone asks, they always decline, they give zero hint about their future coverage. The ethics of ProPublica… everyone should adopt.”

Andrews disputed claims that ProPublica leans too far left.

“I don’t think they lean left. They had a lot of coverage during the Obama administration that was not always flattering. I think they tell the truth from both the left and right side.”

Colodny, a former reporter for Fortune magazine, told The Post that he is “proud to be a longstanding supporter of ProPublica and believe in their mission and the important work they have done over many years. I support ProPublica because I have long been concerned about the crisis in funding for journalism in the US.”

Lawrence Rand also spoke to The Post — although he gave a false name when asked who he was — and echoed what Andrews said about ProPublica’s blemish-free ethics.