The Labour Party says Prime Minister Key has shifted his defence of his embattled minister John Banks.
Opposition parties have renewed pressure on Mr Key to sack Mr Banks as a minister after police files revealed how much he knew about donations made to his Auckland mayoral campaign in 2010.
The police have said the donations, including $50,000 from internet millionaire Kim Dotcom, should not have been declared anonymous but there was not enough evidence to prosecute Mr Banks.
Labour Party leader David Shearer says Mr Key's previous claim was Mr Banks had not broken the law simply because he said so.
But he says now Mr Banks is supposedly innocent because the time ran out on a charge being filed.
Mr Banks, who is also the ACT Party leader, says the Labour Party's allegations against him are politically motivated.
He says the police have already gone through his case intensively and extensively, and did not lay charges against him.
Mr Banks says it is time to move on.
On his way into Parliament on Tuesday afternoon, Mr Banks told reporters the police have already investigated and did not lay charges against him.
"A team of the very best police officers this country could assemble went through this intensively and extensively," Mr Banks said.
"They weighed every word of every witness, every sentence of every witness, every paragraph of every witness, and they concluded no charges. We've moved on."