DJT absolutely knew what he was doing dragging Burisma stuff into the open. Risky move, but he can't lose now:

• Dems de facto nominated Biden as a front runner. Getting rid of him now would be to admit defeat, and worse, to admit that the Obama admin was corrupt as fuck to the very core. The dude forgets which state he's in, and can barely say a sentence without embarrassing himself. He also sniffs children.

• Dems did the impeachment, thereby alienating the swing voters Trump needs to win. This was choreographed by Trump so that it's obvious to everyone that it's bullshit towards the end.