He needs to look like a potential winner not a loser
For the moment at least Mr Corbyn’s authority within the Labour Party derives directly from the sheer scale of his victory in the leadership election in September. His winning margin, of course, was even greater than that of Tony Blair’s in 1994.
So whenever questions are raised as is inevitable within the Parliamentary Labour Party given his lack of support there, his team will point to the September voting figures to assert his authority. That will not always be the case.
For the hard fact is that leaders derive their authority as we get closer to elections from the perception of what that is going to bring.
We saw that during the last parliament with Ed Miliband. Although there were fears that his voter appeal, and therefore Labour’s because of the importance of the leader, might not be as great as the polls were suggesting the voting numbers remained mostly positive. There were rumblings at times during Miliband’s leadership but it was always hard to make the case that things would be better with someone else.
That was unlike Iain Duncan Smith in the Conservative party in 2003. IDS had looked a mistake from the moment he became leader two days after 9/11 in 2001 and never really established any authority. The question was always when he would be ousted not if.
Or look earlier to the dramatic events exactly 25 years ago when Mrs Thatcher looked like a general election loser – a perception reinforced by her party’s defeat in the Eastbourne by-election the previous month. The Tories looked as though they would lose the following election and she had to go.
Fortunately for Mr Corbyn the Labour Party has never had the stomach, for leader defenestrations. Also the rules make it hard. Look at how Gordon Brown was able to to carry on.
Whether that remains the case is hard to say but a leader that looks as though he can’t win is always going to face challenges. With the voting intention polls now having much less influence other indicators like leader ratings and by-elections take on a greater importance.
Mr Corbyn needs a good result in Oldham a fortnight on Thursday.