Andrew Sullivan sums up what we can expect of the next weeks until the November election.

The phoney war is over as the US presidential candidates square up for the most compelling contest in a generation. The eagerly anticipated text message arrived on millions of mobile phones yesterday at 3am. With it, many Americans who had registered to be updated with details of Barack Obama

The announcement was merely the latest dramatic act in what has already been a draining, historic, exhilarating nine months of frantic campaigning. Yet the most important thing dawning on observers of the election, even those who have been examining it under a microscope for months, is that the real campaign starts now - and no one has a clue what is going to happen.

Stop analysing the polls of the past month indicating a surge by John McCain, the Republican nominee. If you looked at the polls at this point in the last two election cycles, you would see they were poised for real movement only now. This, after all, is when the mass of American voters tune in.

Already there are signs that the intensity of the campaigning has increased over the summer. Obama made his first move against McCain six weeks ago with his trip to the Middle East and Europe. It cemented his commander-in-chief potential, especially as the Iraqi government used the opportunity to endorse a US timetable for withdrawal from Iraq, Obama