Shadow home secretary Yvette Cooper has accused Gordon Brown's former aide Damian McBride of being "out of control".
Cooper, whose husband Ed Balls was a key Brownite, told Sky News' Murnaghan programme: "I think this is ... about a kind of politics that really is appalling, that we should never go back to.
"It is something that happened some years ago, but I think it's a sign of how much the Labour Party has changed, the very different climate, the very different way in which Ed Miliband is managing things and operating things now, that's a good thing.
"We don't want to go back to the navel gazing of the past."
More top news
Guillier conceded a "severe defeat" defeat to his supporters as the result came in.
The outage struck Hartfield-Jackson Atlanta International Airport at around 1pm local time, stopping all outgoing flights.
It will be a chilly day for many parts with the highest temperatures, about 10 Celsius (50F) in the far northwest.