Trivia buffs have noted that only U.S. Presidents Barack Obama and Franklin D. Roosevelt have taken the oath of office four times. FDR did so because he was elected president four times. Mr. Obama has done it because he and Supreme Court Justice John Roberts flubbed the first oath four years ago and repeated the procedure a day later to erase any doubts. Again this year, he went through the process twice because he was constitutionally bound to take the oath on Jan. 20 before repeating it a day later for the inauguration crowds.

After Mr. Obama's second inaugural address was delivered last week, observers are seeing much more in common between the two presidents.

Mr. Obama's speech was a full-throated defense of his vision for the country, uniformly described as the most liberal speech delivered by a U.S. president in decades.