Why do you think that writing in the third person is the preferred tone for expository essay writing?

Too much first person looks like self-absorption. Limit it to a few key passages: "I will argue that ... " Third person focuses on the actual topic, not the writer: "Obama campaigned skillfully..." rather than "I was impressed by Obama's campaign."

Note that avoiding first person by using passive voice--an older academic practice--is no longer in fashion. "It is argued that..." Just say, "I argue."