Escaping the latest of a string of steaming hot summer days, I duck gratefully into the cool interior of Tosca, an Italian restaurant in the lobbyist quarter of Washington DC. From the pavement it is not prepossessing, curtains entirely screening off the interior and presenting a blank face to the world. But the busy, clubby interior hums with power. Situated conveniently between Capitol Hill and the White House, and in the neighbourhood of some of Washington’s most powerful political consultancies, it has a reputation as a location for political deals and power-broking at the highest levels. It was here, legend has it, that Tom Daschle spent a five-hour dinner persuading Barack Obama to run for the US presidency. It is very DC.