Brazil's Rousseff tries to boost U.S. ties but state visit up in the air

BRASILIA (Reuters) - Brazil's President Dilma Rousseff, who cancelled a White House trip last year in anger over U.S. spying revelations, now wants to improve ties and reschedule the state visit - but some U.S. officials warn it might not be that easy.

A debate in Washington over whether and when to re-extend the invitation to Rousseff reflects persistent diplomatic strains between the Americas' two largest economies, which have long struggled with different philosophies on trade how to handle regional flashpoints such as Venezuela and Cuba.