Informal

Nixon's style here is peculiar, to say the least. For one thing, it's messy. The opening of the speech is almost rambling, the sentence structure throughout is convoluted and inelegant.

Check out this run-on sentence:

That is not Nixon speaking, but it is an independent audit which was requested because I want the American people to know all the facts and I am not afraid of having independent people go in and check the facts, and that is exactly what they did. (66)

Nixon's trying to present all the information he needs to exonerate himself, but he's doing it as part of a conversation, so he doesn't want to wrap it in legalese that the public might not understand.