The one very big question about Rick Gates' plea deal

(CNN)After weeks of rumors, it became official Friday afternoon: Rick Gates pleaded guilty to two criminal charges and agreed to cooperate with special counsel Robert Mueller's ongoing probe into Russia's attempted meddling in the 2016 election.

Gates, who served as Trump's deputy campaign chairman for a time in 2016, became the third person in Donald Trump's orbit to cop a plea as a result of the Mueller investigation -- joining former national security adviser Michael Flynn and former foreign policy adviser George Papadopoulos as cooperating witnesses.
Mueller's willingness to cut a plea deal with Gates -- coming less than 24 hours after the special counsel's office charged Gates and one-time Trump campaign chairman Paul Manafort with a bevy of money laundering and bank fraud violations -- suggests that Mueller believes that Gates has information critical to his broader investigation into Russian meddling and any possible collusion between the foreign power and the Trump campaign.
    The big question is: What does Mueller believe Gates knows -- and about whom?
    The options, broadly speaking, look like this:
    1. Gates knows about all of Manafort's activities
    Manafort has, to date, denied any and all charges against him -- including the allegations Thursday that he and Gates laundered more than $30 million and didn't pay taxes on it for a decade.
    "The new allegations against Mr. Manafort, once again, have nothing to do with Russia and 2016 election interference/collusion," said Manafort's spokesman on Thursday. "Mr. Manafort is confident that he will be acquitted and violations of his constitutional rights will be remedied."
    Given Gates' long-working relationship with Manafort -- the former has been the latter's wingman in private business and on the Trump campaign for the better part of the last 10 years -- it's possible that Mueller sees Gates as having the goods to convict Manafort on the charges against him.
    2. Gates can help flip Manafort
    It's quite clear from Mueller's aggressiveness regarding Gates and Manafort over the last 48 hours that the special counsel is upping pressure on both men to cut plea deals.
    Gates has flipped. That makes Manafort's situation even more perilous. If Gates worked hand in hand with Manafort for a decade and is admitting that he broke the law -- and is willing to cooperate with Mueller's broader probe -- that leaves Manafort as a man on an island.
    "Notwithstanding that Rick Gates pled today, I continue to maintain my innocence," Manafort said in a statement Friday afternoon. "I had hoped and expected my business colleague would have had the strength to continue the battle to prove our innocence. For reasons yet to surface he chose to do otherwise."
    For all of Trump's attempts to dismiss the role Manafort played -- "Paul Manafort was replaced long before the election took place. He was only there for a short period of time" -- there are two crucial facts to remember about Manafort.
    First, his title was "campaign chairman" but he was really the campaign manager. And he was the manager during a critical time -- as Trump sought to beat back attempts by the GOP establishment to rob him of the delegates necessary to win the nomination outright.
    Second, Manafort was at the famous/infamous June 2016 meeting at Trump Tower between top campaign aides and Russian operatives. That meeting, which was organized under the promise that the Russians had dirt on Hillary Clinton that they were going to share with Manafort, Jared Kushner and Donald Trump Jr. feels like a linchpin moment for Mueller to examine.
    3. Gates has information on other people in Trumpworld
    We assume that Mueller sees Gates as a path to Manafort -- whether for the purposes of nailing the former campaign chairman for his alleged wrongdoing in Ukraine or as a vessel into the innermost sanctum of Trump's inner circle.
    But remember that Gates was in the senior management of the Trump campaign not only from the time Manafort was hired in May 2016 until he was fired in the summer. Gates remained on the campaign, serving as a bridge between it and the Republican National Committee. And, as The New York Times noted, Gates was close enough to the Trump senior brass that he traveled with the candidate on Trump's plane all the way through November 8, 2016.
    Given that, it's possible that Gates has information well beyond Manafort.
    Obviously, these 3 options are not mutually exclusive. Option 1 could lead directly to Option 2. Option 3 could be tied to either Option 1 or 2 (or both).
    But, what Gates knows -- and about who -- is the $1 million question at the moment. If Gates' knowledge is limited to the deals he and Manafort did with Ukraine, that's one thing. If Gates has enough knowledge to convince Manafort that he's out of options and needs to cooperate with Mueller, that's something else entirely.
    It's the difference between small-to-medium potatoes and very, very big ones. Stay tuned.