WASHINGTON (AP) -- Both Chief Justice John Roberts and President Barack Obama stumbled slightly over wording of the presidential oath of office on Tuesday, providing a brief, awkward moment in an otherwise smooth inauguration ceremony.

Initially, Obama interrupted Roberts midway through the opening line, in which the president repeats his name and solemnly swears.

Next in the oath, which is enshrined in the Constitution, is the phrase "... that I will faithfully execute the office of president of the United States." But Roberts rearranged the order of the words, not saying "faithfully" until after "president of the United States."

That appeared to throw Obama off. He stopped abruptly at the word "execute."

Recognizing something was off, Roberts then repeated the phrase, putting "faithfully" in the right place but without repeating "execute."

Obama then repeated Roberts' original, incorrect version: "... the office of president of the United States faithfully."

After that, they were back on track. Except that the oath was taken five minutes late. Technically, Obama was already president anyway -- the Constitution says the term of the incoming president begins at noon on Jan. 20.

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