 I'm Keith Peters reporting. President Biden held a news conference Thursday evening, the key event in a monumental week for his campaign, as he fends off calls for him to step aside as the party's presumptive nominee. His big moment came on the last day of the NATO summit. It got off to an awkward start when the president flubbed an introduction to Ukrainian President Volodymyr Zelensky, referring to him instead as President Vladimir Putin to the gasps of those in attendance.