Could Ken Livingstone really bring Ed Miliband down?

Toby Young, now at the new Sun on Sunday, wrote a piece on 26 February about Michael Gove’s prospects of leading the Conservative party which began:

THERE'S a good deal of speculation in Westminster about who might succeed Ed Miliband if Labour don't start performing better in the polls. The next big test of his leadership will be the London mayoral elections on May 3. If Boris beats Ken, it will be one more nail in Ed's coffin.

The polling so far this year certainly suggests that the race is neck-and-neck between Boris Johnson (Conservative) and Ken Livingstone (Labour), most recently, according to YouGov, at 51% and 49% respectively, when the other candidates have been eliminated. Before that, Boris gets 46%, Ken 45%, Hugh Paddick (LibDem) 6% and others 3%. But as UK Polling Report points out, the YouGov poll shows that in a national election the same Londoners would vote 35% Conservative, 47% Labour and 9% LibDem, a slightly bigger swing towards Labour since the general election than nationally.

Obviously, it would be better for Labour nationally if Ken were to win, but I really can’t see the  party wanting to blame Ed Miliband (42) for the inability of Ken Livingstone (66, a generation older) to stop some of Labour's natural vote defecting to Boris Johnson or to discourage a greater proportion of the LibDems from making him their second choice. Nor is Ed Miliband likely to be blamed for not attempting to obstruct Ken’s adoption as Labour candidate in the first place.