The race now moves onto supporting nominations from constituency Labour parties: who will emerge the strongest?
Mary Creagh remembers her constituency neighbour.
That these institutions attracted someone of Cox's calibre suggests they are in better health than many suggest.
She was always ready to listen, to be creative, to think the unthinkable, and to change her mind.
Labour have triumphed in the Tooting by-election, but the victory was overshadowed by the killing of Jo Cox.
The Labour MP and humanitarian I came to know was the type of person who would restore one's faith in politics.
Both Leave and Remain have suspended their campaigns, and the BBC has cancelled Question Time tonight.
Jo Cox, the MP for Batley and Spen, has died following an attack outside a constituency surgery she was holding in a local library.
The European Union is a barrier to a progressive government, says Graham Stringer.
The party's strategists have been gleefully compiling instances of Conservative attacks on the government's own record.
A new IpsosMori survey explains what's going on - and offers hope to both sides.
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