Society wants more regulation of tech companies but no one knows how that looks.

Congresswoman Alexandria Ocasio-Cortez is taking on Big Tech. On Friday (Jan. 25) she sent a letter, along with fellow US representative Chellie Pingree of Maine, to the CEOs of Microsoft, Facebook, and Google, expressing her disappointment in the companies’ decision to sponsor LibertyCon, a libertarian student conference that was held in Washington earlier in January, and included an event devoted to climate change denial.

The letter points out the hypocrisy of the companies’ previously stated devotion to the issue:

The past commitments of your companies to address climate change have been well documented. We are encouraged that each of you have pledged to reduce your carbon footprint and have committed other efforts like pursuing renewable energy. We need more of this commitment from corporate America. Disappointingly, though, the example you have set promoting sustainability and evidence-based science is compromised by your implicit support of the session organized at LibertyCon.

The session that the two congresswomen are referring to is likely a presentation by a retired statistics professor Caleb Rossiter, who claims that rising carbon dioxide levels are good for the planet, according to Mother Jones, which first reported on the conference. LibertyCon also happened to host a session called, “Socialism Is Evil,” which directly referenced Ocasio-Cortez and senator Bernie Sanders.

“Every year, we sponsor organizations from across the political spectrum to promote strong technology laws,” a Google spokesperson said in a statement to Quartz. “As we make clear in our public policy transparency report, Google’s sponsorship or collaboration with a third party organization doesn’t mean that we endorse the organization’s entire agenda or agree with other speakers or sponsors.”

Facebook sent Quartz its engagement report, which outlines its sponsorship policies, and pointed out that only two sessions at the event were about carbon dioxide levels, the other being a debate about carbon taxes.

Microsoft said in a statement to Quartz that its engagement with LibertyCon was through a reception for students to discuss topics like rural broadband and privacy. “Climate change is one of the most important issues of our time, and our commitment to addressing it is unequivocal,” the company said. “For the past decade, we’ve reduced emissions, invested in renewable energy, supported policies to address climate change and enabled people around the globe to use technology to accelerate progress on this issue.”

Tech companies like to underline that they engage with groups from across the ideological gamut, while often being attacked by conservatives for alleged left-wing bias.

The letter from Ocasio-Cortez and Pingree included what is difficult to read as anything other than a dig at Facebook and Google, and their role in the rise of the phenomenon of fake news. “As you are well aware, the spreading of misinformation can be dangerous to our society,” the congresswomen wrote.

Over the weekend, Ocasio-Cortez also knocked tech companies on Twitter for contributing to the demise of journalism, following a week of hundreds of layoffs in the industry in the United States.