looming over all this, of course, president trump and his very big shadow, so let's go to our chief political correspondent dana bash. dana, you have a big night ahead of you. talk me through the big themes for today. >> let's start with what you just laid out there the president. he looms large on and over pretty much everything in politics and elsewhere. and what's going to be interesting to look for is how he plays in different kinds of races. so first and foremost, we have this special election in ohio. it's been a republican seat for almost four decades where democrats haven't even come close and polls show that the democratic candidate there is coming close. the president went out over the weekend and campaigned for the republican troy balderson. republicans i talked to say that that was really, really critical to getting the base gined up.