President Joe Biden worked to put fears about his age and fitness to rest with a rousing press conference at the NATO summit, where he demonstrated a commanding grasp of foreign policy issues, took potshots at former President Donald Trump, and reiterated his commitment to remain in the presidential race. But for the first time, suggested CNN political commentator David Chalian, there seemed to be a slightly different tone about that commitment. “Did the president put concerns about his candidacy to rest tonight?” asked Anderson Cooper. Want more breaking political news? Click for the latest h…