They have no dirt on him or they would have used it before the election.
“They have no dirt on him or they would have used it before the election.”
Manafort was the original ingredient in the plot but needed some more spice to it. Hence the attempts at dirtying up staffers and the Trump Tower setup. I think they were hoping for an October surprise, but it fell apart when the Manafort story leaked prematurely in August.
Here is a refresher article from March 2018 by Jeff Carlson. It gives the Manafort timeline.