Facebook CEO Mark Zuckerberg has announced plans to meet with conservative leaders to address allegations that his website's Trending Topics section suppresses conservative news and news outlets.

Before that, it seems Zuck will be answering to the US Senate Commerce Committee, who sent him a letter asking key questions about how Trending Topics are selected.

The letter was a reaction to a report from Gizmodo that purports to pull back the curtain on that section's operations. Its sources such as former contractors who say they worked on the section, which reaches Facebook's massive, roughly 167 million-person audience.

"This week, there was a report suggesting that Facebook contractors working on Trending Topics suppressed stories with conservative viewpoints," " Zuckerberg wrote in a Facebook post. "We take this report very seriously and are conducting a full investigation to ensure our teams upheld the integrity of this product."

In a press release from Facebook, vice-president of global operations Justin Osofsky scratched the surface of how Trending Topics works, stating that it's "governed by a set of guidelines meant to ensure a high-quality product."

But what are those? That's what the Commerce Committee wants to know: "When did Facebook first introduce these guidelines?" their letter asks, furthermore requesting that the company "please provide a copy of these guidelines."

According to the original report, a former contractor with the Trending Topics team alleged that the section is rather arbitrary, full of hand-picked injections of news rather than items selected purely by algorithm, and that guidelines, stated or implied, censored news related to popular conservatives. "I believe it had a chilling effect on conservative news," that source said.

While Zuckerberg writes that "we have found no evidence that this report is true," he's playing offense as well as defense. "In the coming weeks, I'll also be inviting leading conservatives and people from across the political spectrum to talk with me about this and share their points of view," the CEO writes. "I want to have a direct conversation about what Facebook stands for and how we can be sure our platform stays as open as possible."

One noted conservative and die-hard Trump booster, Breitbart's Milo Yiannopoulos, appears to want in. "Users deserve to know whether the Trending Topics on Facebook really are trending or whether it's just something that some social justice warrior in San Francisco wants you to believe is popular," he says in a Youtube video written up by CNN. "I think it's time you answered your users and I think it's time that you sat down with me." Yiannopoulos hopes a conversation between them might be live-streamed to Facebook.

In the past, Zuckerberg has scrupulously avoided political labels of his own. In 2013, while pushing for immigration reform, CNN says he finally pinned himself down. "I'm pro-knowledge economy," he said.

Previously:Facebook Denies Allegations About Cherrypicking News As Senate Opens Inquiry