A.T. Robertson Commentary Luke 9:19

"And they answering said, John the Baptist; but others [say], Elijah; and others, that one of the old prophets is risen again." — Luke 9:19 (ASV)

That I am (με εινα). Accusative and infinitive in indirect assertion, a common Greek idiom. Matthew 16:13 for "I" has "the Son of man" as identical in the consciousness of Christ. The various opinions of men about Jesus here run parallel to the rumours heard by Herod (verses 8,9).