I’ve read a lot of speculation about why Steve Bannon was subpoenaed to appear before one of Special Counsel Robert Mueller’s grand juries. It has been noted that Bannon is getting different treatment than other current and former senior administrative officials who have voluntarily spoken with the Department of Justice’s independent Russia investigation. Cooperating officials like Sean Spicer, Hope Hicks, and Reince Priebus were not compelled to testify and they did not have to face grand jurors. So, what’s different about Bannon?

A common idea is that this has something to do with the publication of Michael Wolff’s book Fire and Fury in which Bannon makes a series of accusations, including that Trump Jr., Manafort and Kushner engaged in treasonous behavior and that the administration would ultimately get nailed by Mueller for money laundering activities. Supposedly, these statements have piqued Mueller’s interest, but that would only explain why he wants to talk to Bannon and not why he would subpoena him. Others have speculated that Mueller wants to question Bannon before he can tell Congress what he knows because that will obviously leak back to the administration. But Bannon was scheduled to testify to Congress today, and it was only because the White House asked him not to cooperate that he didn’t provide his testimony. The House Intelligence Committee issued their own subpoena on the spot and presumably he will be compelled to talk to them very soon.

Now, it could be that Mueller is bringing Bannon in because of Wolff’s book or because he’s now being hauled before Congress, but I think the timing here is probably coincidental. Mueller wants to talk to Bannon about something else. He wants to talk to him about Cambridge Analytica.

To begin with, the things Bannon was quoted as saying in Wolff’s book aren’t of that much use to Mueller. Bannon wasn’t part of the campaign when Trump Jr., Kushner, and Manafort met with the Russians in Trump Tower. His knowledge of money laundering is probably indirect at best. He may have heard or learned things of interest of Mueller, but his firsthand knowledge of Trump’s business practices is probably nonexistent and he’s not a helpful witness to things that happened before he was hired to run the Trump campaign. Mueller wants Bannon to tell him things that can be used in court, and if he’s trying to build a collusion case then he wants Bannon to explain everything he knows about Cambridge Analytica.

Steve Bannon is a former vice president of Cambridge Analytica. Since at least May, Congress has been investigating the possibility that Cambridge Analytica colluded with Russia to help their trolls and bots target Americans for Trump’s best advantage in the election. FBI counterintelligence officers have been looking at this scenario since at least March.

As they dig into the viralizing of such stories, congressional investigations are probing not just Russia’s role but whether Moscow had help from the Trump campaign. Sources familiar with the investigations say they are probing two Trump-linked organizations: Cambridge Analytica, a data-analytics company hired by the campaign that is partly owned by deep-pocketed Trump backer Robert Mercer; and Breitbart News, the right-wing website formerly run by Trump’s top political adviser Stephen Bannon…

…In March, McClatchy newspapers reported that FBI counterintelligence investigators were probing whether far-right sites like Breitbart News and Infowars had coordinated with Russian botnets to blitz social media with anti-Clinton stories, mixing fact and fiction when Trump was doing poorly in the campaign.

There’s an obvious nexus here. Cambridge Analytica was founded by Robert Mercer. Robert Mercer became the most important funder of Breitbart News which was run by Steve Bannon. Steve Bannon became a vice-president of Cambridge Analytica. Bannon introduced Cambridge Analytica’s CEO Alexander Nix to the Trump campaign in May 2016. Jared Kushner hired Cambridge Analytica in June 2016. Mercer convinced Trump to hire Steve Bannon in August 2016.

More information has come to light already. There was the strange case of the longtime Republican operative Peter W. Smith who committed suicide shortly after confiding in a Wall Street Journal reporter that he had been working with Michael Flynn and his son to find hackers, including Russian hackers, who had obtained or who could obtain the emails that Hillary Clinton had deleted from her private server. Then Michael Flynn was forced to amend his financial disclosure statement to reveal that he’d been under contract to Cambridge Analytica.

Then this happened:

On October 25th, 2017, Julian Assange confirmed on Twitter that he had been approached by Cambridge Analytica, but said he had rejected its proposal. Assange’s tweet followed a story in The Daily Beast alleging that Cambridge Analytica chief executive Alexander Nix had proposed a collaboration with Wikileaks to find the 33,000 emails that had been deleted from Clinton’s private server. CNN said it had been told by several unnamed sources that Nix intended to turn the Clinton email archive released to the public by the State Department into a searchable database for the campaign or a pro-Trump political action committee.

It should not need to be said, but these efforts to obtain Clinton’s deleted emails were criminal in nature. The goods they were seeking were only obtainable by hacking into the computer server Hillary Clinton maintained while serving as our Secretary of State. By encouraging people to commit a cybercrime, including foreign nationals, against a U.S. government official, these folks were already engaged in an illegal conspiracy of massive proportions with potential national security implications. Peter W. Smith committed this crime. Michael Flynn and his son committed this crime. The CEO of Cambridge Analytica, Alexander Nix, committed this crime. So, I think it shouldn’t be too hard to see why Steve Bannon should be questioned about all of this considering the intersection of his roles as CEO of Breitbart News, vice-president of Cambridge Analytica and campaign chairman of the Trump campaign.

I’ve already written about the Trump team’s strange obsession with the 33,000 emails Clinton deleted from her server and how it was probably based on a misunderstanding of what George Papadapoulos was told by his Kremlin handler, Prof. Joseph Mifsud.

One part of the puzzle I think is solved. The Trump folks knew the Russians had emails but they didn’t initially know that the source was the DNC and they wrongly assumed that they were from Clinton’s private server. Nonetheless, they eagerly sought to convince the Russians to deliver the damaging information, and that desire explains a lot of their behavior at the time.

Somehow, even after the DNC (and other) leaks started coming out, the belief that the 33,000 emails were out there somewhere never died. That’s why Michael Flynn and Peter W. Smith were still looking for them around Labor Day.

Mueller is definitely interested in that whole sad saga, but he’s more interested in examining the possibility that there was a firmer and more consequential kind of collusion. Did Cambridge Analytica help make Russia’s trolling more effective? Did they share information with the Russians and/or did the Russians share information with them?

The investigators have undoubtedly built a massive dossier on this aspect of the case. On December 15th, the Wall Street Journal reported that Mueller was coming after Cambridge Analytica with both barrels blasting:

Special Counsel Robert Mueller has requested that Cambridge Analytica, a data firm that worked for President Donald Trump’s campaign, turn over documents as part of its investigation into Russian interference in the 2016 U.S. election, according to people familiar with the matter.

Mr. Mueller asked the firm in the fall to turn over the emails of any Cambridge Analytica employees who worked on the Trump campaign, in a sign that the special counsel is probing the Trump campaign’s data operation.

So, it’s true that Bannon might have some information about the obstruction aspects of the case, like the firing of James Comey, but it’s the collusion area that has the most potential to end this presidency. And I’ll bet that Bannon has been subpoenaed to talk primarily about evidence that Mueller has collected from an examination of Cambridge Analytica’s role in the campaign.

One thing we learned from Michael Wolff’s book is that Bannon was pretty much alone in thinking that Trump might actually win. Perhaps he knew something others didn’t, and perhaps Mueller has enough evidence now to ask Bannon about it.