"...The White House stopped just short of dismissing Donald Trump as a clown Sunday - calling him a "sideshow" act with "zero chance" of becoming president. Trump countered that he represents Obama's biggest nightmare in the 2012 race and that the White house is running scared. "I know for a fact that I am the only candidate they are concerned with," Trump told The Daily News. "They are very concerned because I am challenging him as to whether or not he was born in this country where there is a real doubt."
The NY Daily News has details here.