Barack Obama is heading for a landslide victory over John McCain in 12 days’ time if his double-digit poll leads prove accurate and sustained, says a growing consensus of Democratic and Republican political forecasters. No candidate with this big a lead at this late stage of a presidential election has yet gone on to lose.

On Wednesday, a Reuters/Zogby poll gave Mr Obama 51.6 per cent against 42 per cent for Mr McCain – in line with polls this week that have given Mr Obama a lead of between 6 and 14 points.