Oona King in bid to be London's mayor in 2012

The former Labour MP Oona King is to announce her return to frontline politics by declaring that she will challenge Ken Livingstone to become Labour's candidate for mayor of London in 2012. King will fight Livingstone to become Labour challenger to Boris Johnson. The contest – like the leadership fight – will be decided at the party conference in the autumn. News of King's bid came as there were signs of fractiousness over the way leadership contenders solicit backing from their parliamentary colleagues. Candidates have to notch up 33 names before they can take part in the hustings in June and July before voting starts in mid-August. On Sunday, MPs supporting Ed Miliband were accused of telling those who might back his brother David that the former foreign secretary lacked "the human touch". Supporters of John McDonnell were also accused of telling new MPs backing Diane Abbott that their standing in the parliamentary party would be diminished because Abbott was not a "real leftwinger". Whether McDonnell and Abbott make the next round may depend on whether either of them can widen their appeal beyond the same band of 20 to 30 MPs who broadly belong to the parliamentary socialist campaign group. One problem has been that the home phone numbers of many new MPs have proved difficult to track down for discreet canvassing. Ed Miliband today received the endorsement of former Labour leader Neil Kinnock while Burnham won the support of former home secretary David Blunkett. David Miliband has announced 38 MP supporters, Ed Balls 20, Ed Miliband 18 and Andy Burnham 14. McDonnell has two, but more than 150 MPs are still to make up their minds before 9 June.