From NBC's Scott Foster
President Obama just congratulated the son of his 2008 Republican rival, John Sidney McCain IV, as the younger McCain today became the fourth McCain to graduate today from the U.S. Naval Academy.
As the two shook hands at the academy's commencement ceremony, the applause from the crowd was slightly more pronounced compared with the other graduating midshipmen.
Father John McCain was in the audience for the graduation.
While Obama didn't refer to the Arizona senator in his graduation speech, earlier today he acknowledged McCain's presence at the graduation during a bill signing ceremony on reforming the Pentagon's weapons acquisition program. "Sen. McCain couldn't be here today, because he's making sure he has a good seat to watch his son graduate from the Naval Academy in a few hours. And that's where I'm headed as soon as I catch my ride over here."