US President Barack Obama was quoted on Friday as saying that he was "embarrassed" for the 47 Republican senators who wrote a letter to the Iranian government threatening to undermine any agreement reached regarding Tehran's nuclear program.In an interview with Vice News, the president said that the letter was "close to unprecedented.""I'm embarrassed for them," the president told Vice News. "For them to address a letter to the ayatollah ... who they claim is our mortal enemy, and their basic argument to them is, 'Don't deal with our president because you can't trust him to follow through on an agreement.' That's close to unprecedented."