 Growing skepticism about President Joe Biden's re-election chances has European leaders heading into the NATO summit in Washington, confronting the prospect that the military alliance's most prominent critic, Donald Trump, may return to power over its mightiest military. Trump, who before and after his presidency spoke admiringly of Russian President Vladimir Putin and harshly of NATO, often focuses complaints on the U.S. share of the alliance's costs. NATO Secretary General Jens Stoltenberg told CBS' Space the Nation NATO leadership remains strong under President Joe Biden.