Kevin Warsh may be gearing up for the toughest job in the US government as new chairman of the Federal Reserve: He needs to stay true to his rep as a hawk on inflation — while at the same time playing nice with the guy who just nominated him. The latter happens to be President Trump, whose instincts are to rev the economy to 6% growth and worry about inflation later. His instincts are also to jawbone any Fed chair to make that happen even if it means slashing interest rates to zero. If anyone can walk this ...