I may be reading too much into this, but that's interesting phrasing. It doesn't say a thing about whether anyone else in the campaign might have colluded.
It does, doesn't it. If it comes out that someone did collude, he'll deny knowing that.
Also not that
Kushner had no improper contacts.
Kushner has not relied on Russian funds to finance his business. Not a peep about his in-laws or the campaign.
Of course, given what we've seen so far, this could just be elementary precaution on his part. Unless he's personally audited all the Trump organization's books, he can't know. And he's presumably smart enough to not believe anything his father- or brothers-in-law tell him.
