Donald Trump is facing bipartisan pressure to adopt a more presidential tone in his White House run including from Democratic President Barack Obama and Republicans who worry his missteps may do irreparable harm to the party and his campaign.
The Republican front-runner came under fire from Obama on Friday over his recent comments that he will not rule out using nuclear weapons in Europe and that Japan and South Korea might need nuclear weapons to ease the U.S. financial commitment to their security.
"The person who made the statements doesn't know much about foreign policy or nuclear policy or the Korean Peninsula, or the world generally," Obama told a news conference at the conclusion of a nuclear security summit in Washington.