Jeremy Corbyn: 'Jury out' on Labour leader, says union boss
A senior union leader had said "the jury is still out" on whether a Jeremy Corbyn-led Labour Party will be able to "reach out" to the public.
GMB boss Sir Paul Kenny said Mr Corbyn should be judged by how Labour did in elections and not by the enthusiasm shown by many Labour activists to him.
"The rallies are not enough... to say people will rush to Labour," he said.
Mr Corbyn has completed his new shadow cabinet, saying it is a "great" team, drawing on all sections of the party.
After his resounding victory on Saturday, Mr Corbyn has named a 31-strong shadow ministerial team, appointing close ally and fellow left-wing MP John McDonnell as shadow chancellor and giving key jobs to Andy Burnham, Hilary Benn, Heidi Alexander and Lucy Powell.
Unlike other leading unions, which backed Mr Corbyn, the GMB did not endorse any candidate.
And speaking to BBC Radio 4's World At One from the TUC Congress in Brighton, Sir Paul refused to be drawn about Mr Corbyn's long-term prospects, saying it was too early to say whether he would lead the party into the next election.
He likened the new shadow cabinet to "a train of very, very many carriages".
He added: "I don't think the rallies themselves, as enthusiastic as the support was, at this stage is enough for me to say, 'Well I think wherever we go in the country, people will flock to Labour.'
"Let's see how we get on, let's see the real tests, let's see how the public react and let's see how effectively when the tests come, whether they are by-elections, or local government elections or indeed the elections of mayor in London next year.
"Lets see what the voters say. Because at the end of the day, they are really the important ones."
These comments were reinforced by the TUC's general secretary, Frances O'Grady, in her speech to the annual congress.
She warned Labour it must "appeal to the country at large" and aim to win the next election, urging Mr Corbyn and his colleagues to "look sharp, pull together... and get stuck in and oppose".
But a senior union source told the BBC that Mr Corbyn had made "several mistakes" in his first 48 hours as leader of the opposition - chief among them the appointment of Mr McDonnell as shadow chancellor, adding that Angela Eagle would have been a better choice.
The source also said the shadow cabinet "feels too London-y" - with MPs representing constituencies in the capital holding the top two jobs in the Treasury team as well as health and international development.