President Obama, currently visiting the UK as part of his final year in office farewell tour, has come out firmly in favour of the UK remaining in the EU. He emphasised that the USA would give preference to dealing with the EU with the UK being "at the back of the queue".
Leave campaigners have been scornful of his intervention and Boris Johnson accused him of hypocrisy in that he was advocating policies for us that that he would never apply to his own country.
Boris is wrong on the biggest issue here. The US is itself a federation of states, each of which has chosen to join. From the other side of the Atlantic, it looks as though the EU is slowly moving down the path the Americans took more than two hundred years ago. Obama takes for granted the benefits of such a union and is therefore only voicing the obvious when he relates his own country's policies to ours. Whether he should have intervened at all is another question. Let us answer it with a simple analogy, one that the Americans themselves have made. I see my friend about to drive off, having drunk more than enough to impair judgement. Do I say something or do I say "No, I must not interfere with his right to injure or kill himself and others?". No-brainer.
Finally, consider that Obama will say whatever he thinks is right for America. In other words, his comments are based on a hard-headed assessment of US interests. So do their interests and ours coincide? In general, yes they do. We want to trade freely with the US and we want US investment here. Our cultures and histories are closely aligned. We are military allies. Would Obama want us to undertake a course of action that would weaken us? Clearly not. When he advises us to remain in the EU he is not trying to make his country better off at our expense - he is trying to do the best for us both.