(CNN) Former Trump campaign chairman Paul Manafort and special counsel Robert Mueller have been spending a whole lot of time together of late, according to CNN's Katelyn Polantz and Evan Perez . The duo write:

"[Manafort] and his lawyers have visited Mueller's office in Washington at least nine times in the last four weeks, a strong indication that the special counsel is moving at a steady clip."

Wait, what?

In each episode of his weekly YouTube show, Chris Cillizza will delve a little deeper into the surreal world of politics. Click to subscribe!

Which is very interesting considering that President Donald Trump has spent months (and months) downplaying his ties to Manafort and the charges against his former campaign chairman. "I think it's a very sad, sad situation," Trump said of Manafort in an interview with the Associated Press earlier this week . "And there's another thing that had nothing to do with me. That was from years before. You do understand that, right? Do you understand that?"

I DO understand that! When Manafort pleaded guilty last month to one count of conspiracy against the US and one count of conspiracy to obstruct justice due to attempts to tamper with witnesses, that was in relation to his dealings with the Ukrainian government more than a decade prior to his signing on with Trump in the spring of 2016.

But here's the thing: Manafort's cooperation deal with Mueller wasn't about his dealings with the Ukrainians. It was about the light Mueller's team believed he could shine on a variety of aspects of the Trump campaign -- for the critical five months he ran it, a period that included Trump's clinching of the nomination and the formalizing of that fact at the Republican National Convention in August 2016. And we know that Manafort's potential legal peril rests, in large part, on how much his cooperation helps the fill in the blanks the Mueller investigators want filled in.

"[Manafort] also admitted to all the other crimes Mueller accused him of since last October -- from money laundering and bank fraud to foreign lobbying violations related to his work for pro-Russian Ukrainians. Those charges will be dropped if he completely complies with the cooperation agreement...

"Special counsel's office senior prosecutor Andrew Weissmann told the judge that under Manafort's plea agreement, the other charges will be dropped after he is sentenced in both Virginia and DC 'or at the agreement of successful cooperation.'"

each visit. That's more than 50 hours that we know Manafort has spent in Mueller's offices in just the past 28 days! Which gets us back to the news from Polantz and Perez : That Manafort has been to the special counsel's offices at least nine times over the last four weeks. And there's more! According to the CNN report, Manafort is in the Mueller offices for around six hours atvisit. That's more than 50 hours that we know Manafort has spent in Mueller's offices in just the past 28 days!

Consider how bananas the media went -- and rightly so! -- when we learned that now ex-White House counsel Don McGahn had spent more than 30 hours over nine months talking to Mueller and his team. Manafort has well exceeded that amount of face time with Mueller in just the last month. And unlike McGahn, Manafort has a plea deal that expressly states that his level of cooperation will determine the penalties he eventually faces.

In short: This feels like a VERY big deal.

Now. We don't know what Mueller is asking Manafort about -- or what Manafort knows and/or is telling Mueller. It's possible that Manafort is simply verifying lots of details -- not necessarily ones that implicate Trump or his inner circle -- that Mueller and his team have gathered since the start of the investigation 17 months ago.

But, but, but -- what we know about Manafort is that he was at the head of Trump's campaign during a series of events that Mueller is looking into, most notably the June 2016 meeting between top Trump aides and Russians promising dirt on Hillary Clinton.

Manafort was one of only three Trump people in that Trump Tower meeting -- Donald Trump Jr. and Jared Kushner were the other two. The fact that Mueller and his investigators are now inside that room is a BIG deal -- especially when you consider that Manafort has spent more than 50 hours with Mueller over the last month.

Again, nothing may come of all these Manafort-Mueller meetings. But it's hard for me to see why Mueller would spend so much time with Manafort -- especially this far along in the investigation -- if the former head of the FBI didn't believe that Manafort had something (and maybe a lot of somethings) to give him that will help the probe.

All of which should make the White House more than a little nervous.