US President Donald Trump voiced confidence on Wednesday in embattled British Prime Minister Boris Johnson, insisting: "He knows how to win."Johnson faces a revolt in the House of Commons over the possibility of a no deal exit from the European Union, but Trump told reporters his friend was "going to be okay"."Boris is a friend of mine, and he's going at it. There's no question about it," he said."I watched him this morning. He's in there fighting. He knows how to win. Boris knows how to win. Don't worry about him. He's going to be okay."