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Phrase(s): (I) can’t say that I do. [and] (I) can’t say’s I do.; (I) can’t say (as) I do.
Fig. a vague response to a question about whether one remembers, knows about, likes, etc., something or someone. (The say as and say’s are not standard English.) • Jane: You remember Fred, don’t you? John: Can’t say as I do. • Bob: This is a fine looking car. Do you like it? Bill: I can’t say I do.
McGrawhill's American Idioms And Phrasal Verbs