Edward Luce is the Washington bureau chief of the Financial Times, London.

We are in the closing days of the third US presidential election since September 11 2001. Yet the shadow cast by the Twin Towers attacks has barely receded. In the final debate on Monday night, the killing of the US ambassador in the Libyan city of Benghazi is likely to be the most bitter point of contention between Barack Obama and Mitt Romney. Christopher Stevens and three others died on the 11th anniversary of 9/11. Mr Romney has been trying to make capital out of it ever since.

On Monday night Mr Romney will get what further help, or rope, he needs from Bob Schieffer, the CBS moderator. Mr Schieffer has allocated two-thirds of the debate to the Middle East. Of his six topics, two are devoted to "the new face of terrorism in the Middle East", which means Benghazi. Libya may thus get as much time as "The rise of China" and "America’s role in the world" put together. The other topics are Israel and Iran, and Afghanistan and Pakistan.

Mr Schieffer’s list highlights 9/11’s continued hold on the American debate. The 2012 election as a whole shows that the US has not yet left the George W. Bush era behind. The two nominees are essentially offering contrasting versions of Mr Bush’s presidency. Mr Romney promises a return to the unilateralism of his first term. Mr Obama will continue with the lighter touch of Mr Bush’s second. It certainly offers a choice. But it also reflects America’s weak appetite to talk about so many other challenges before it... ..