Trevor Mallard is taking responsibility for the Labour Party leader's blunder in Parliament yesterday.
David Shearer went for the Prime Minister's jugular when he brought up a past quote, in an attempt to prove John Key's hypocrisy for not sacking John Banks.
But he missed by a mile - it turns out the quote was from National-leaning blogger David Farrar.
Mr Key had never uttered the words and David Shearer had to return to the House last night to apologise.
Mr Mallard this morning told RadioLIVE he was to blame.
"It's a terrible mistake and I take responsibility for that," says Mr Mallard, who still managed to get in a dig at the Prime Minister.
"We confused David Farrar with the Prime Minister – they both say the same things all the time, and the quotes got shuffled.
"I looked at the questions beforehand, I should have seen the difference."
RadioLIVE / 3 News