US President Joe Biden appealed Thursday for a united front against hate-crimes and political violence in a speech building on his bid to present himself as champion of moderate values at a time of rising extremism. “We have to face the good, the bad and the truth. That’s what great nations do and we’re a great nation,” Biden told a packed hall at the White House’s United We Stand Summit. “You must choose to be a nation of hope, unity and optimism – or a nation of fear and division and hate.” Biden recounted, as often before, how he took the decision to challenge then president Donald Trump in…