Ah, if you had mentioned Obama I might have searched for something that He had said, dj, instead of something one of our homegrown popliticos had said. We don't all scan the political news each morning for the latest offering, to keep our blood pressure topped up.
I still think there is a wide gap to leap between saying that there could be higher tariffs in the US if Britain leaves the EU, which some US firms might not want to meet, and saying that the US might not trade with Britain. There are a lot of firms in the US, "some of them" does not make up the whole of the States. You make it sound as though the entire country would dump Britain immediately!
As it happens it was not in fact Obama but Michael Froman, President Barack Obama's trade adviser, who said most on the subject. his statement is condemned as "ugly scaremongering" by Nile Gardiner (Director of the Margaret Thatcher Center for Freedom at the Heritage Foundation in Washington, DC)
"It is very hard to see the United States post-Obama raising trade barriers against a nation that more than any other in the world shares with it a common culture, history and language, and whose economies, militaries, and intelligence agencies are so deeply intertwined."