...But it was an unprecedented margin of victory for a candidate that was almost written off...
Not completely unprecedented. Remember the Dewey Defeats Truman headline?
1948 Truman versus Dewey electoral vote count..
Truman 303. Dewey 189
Was reading about the Truman campaign in 1948. Very similar. Truman ignored the polls and went right to the people giving speech after speech. Like Trump, Harry worked his ass off while the other side took victory for granted.