text:  And we preview the stakes for NATO leaders landing in Washington for this week's Summit of the Alliance. First, the news. Live from NPR News in Washington, I'm Jack Spear. The White House came under intense questioning today about President Biden's health. As NPR's Asma Hawley reports, this all follows the president's recent rocky debate performance. There have been calls from some Democrats for Biden to drop out of the presidential race amid questions about his age and his health.