We don’t know much more. The White House press secretary, Sarah Huckabee Sanders, and Rudy Giuliani, Trump’s lawyer, both told NPR and Politico that Manafort’s cooperation has nothing to do with Trump’s campaign. If so, it is unclear why Mueller—who is tasked with investigating the possibility of that campaign having colluded with Russia—would make an agreement that is predicated on cooperation. The plea agreement specifically requires Manafort to disclose to the government “his participation in and knowledge of all criminal activities.”
“We might not know what Manafort will tell them, but Mueller knows,” Benjamin Wittes, of the Brookings Institution and the editor of its Lawfare blog, told me. He pointed out that the plea agreement refers to a proffer session, earlier in the week, “in which the prosecutors will have sussed out what Manafort might be able to contribute.”