Президент Оба́ма does a great job speaking to people as long as he’s got a teleprompter in front of him. When he doesn’t, he’s got a lot of “um"s and “ahhh"s as he attempts to put together a string of words.
And if he strolls down to where the White House Press Corps works? Well he’s only there to visit them, not to take any hard questions from them:

According to reports, when the Politico’s Jonathan Martin asked the president about his nominee for deputy secretary of defense, William Lynn, Obama refused to answer, saying he was not there to take questions.
“I came down here to visit. I didn’t come down here—this is what happens. I can’t end up visiting you guys and shaking hands if I am going to grilled every time I come down here,” the president said.
Pressed further by the Politico reporter about his Pentagon nominee, Obama turned more serious, putting his hand on the reporter’s shoulder and staring him in the eye.
“All right, come on” he said, with obvious irritation in his voice. “We will be having a press conference, at which time you can feel free to [ask] questions. Right now, I just wanted to say hello and introduce myself to you guys—that’s all I was trying to do,” Politico.com reported.

Note to Reporters: you are to ask serious questions of The One™ when he’s in his environment, not when he’s in yours.