Cunliffe says he has no recollection of writing it. That his office has no record of the letter. And, anyway, that the letter was of a kind that MPs write all the time for constituents.
However, the letter highlights Liu's intention to set up business in New Zealand and export "huge quantities" of agricultural and horticultural products to China.
If that is not advocating for residence to be granted, it strays perilously close to doing so.
In an ideal world, Cunliffe would have tendered his resignation as Labour's leader, at which point his colleagues would have expressed their confidence in him keeping his job and carrying on as normal.
That way Cunliffe would have been seen to have atoned somewhat for being found to have not told the real story about Liu.
The risk would have been that his fellow MPs accepted his resignation. If the polls get even worse for Labour, they may yet demand it.
Cunliffe may yet be saved by a couple of factors.
First, taking over the leadership just three months before the election could turn out to be a very poisoned chalice for Robertson.
Second, Cunliffe was the popular choice for leader of the wider membership and trade unions affiliated to the party.
Robertson knows that removing Cunliffe through a caucus majority alone - as allowed under Labour's emergency rules supposedly catering for the death of a leader close to an election - would destabilise the wider party and destroy what morale remains among Labour's activist base.
That is hardly the scenario a new leader would want to take into an election campaign.
Debate on this article is now closed.