Labour hires top Barack Obama aide in bid to oust Boris Johnson Mr Miliband has called in Arnie Graf, 68, whose community organising skills were honed in Mr Obama's heartlands of the South Side of Chicago, to search out Labour voters in unpromising territory for the party, particularly London's outer suburbs. The contest on May 3 will see voters rank candidates in order of preference, with the result that - with a series of "rounds" with the least popular candidate dropping out each time. The final three are expected to be Mr Johnson, Mr Livingstone and Brian Paddick, the former Metropolitan Police commander who is the Liberal Democrat candidate. A senior Labour source said: "The problem is we have very little organisation in the outer ring of the 'doughnut" - the outer London boroughs. There are Labour voters there though, and while their votes might count for little in a general election they could be crucial in a tight mayoral contest.