”IN JULY 2008 Barack Obama, then a candidate for the presidency, declared before an adoring crowd in Berlin that “true partnership and true progress [require] constant work and sustained sacrifice.” So it is with free trade. If not championed by leaders who understand its broad benefits, it will constantly be eroded by narrow economic nationalism. Mr Obama now appears to be surrendering to protectionists within his own party. If he cannot drag Democrats back to their senses, the world will lose its best opportunity in two decades for a burst of liberalisation. It will also be a signal that America is giving up its role as defender of an open global economy in the same way that Mr Obama has retreated in foreign policy.