If your experience is in the government sector, it will be harder, as government agencies don't sponsor at all, and accounting firms that do government work may not think your government experience will help in the US. You might look at big accounting and consulting firms that work with UK companies that operate in the US. Again, that government thing will be a problem. When I worked for one of the Big 8, back when there was a Big 8, all the government work was done out of the Washington DC office, and it wasn't a very big office, either.