ACT leader Rodney Hide says David Garrett still has his backing as an MP, despite a disclosure that he used a dead child's identity to fraudulently obtain a passport.
Mr Garrett on Wednesday admitted in Parliament to committing passport fraud in 1984. The crime was uncovered in 2005, when he was discharged without conviction.
Mr Hide told Television New Zealand's Close Up programme that Mr Garrett told him about the matter when he asked him to stand for ACT at the last election.
He said that it did not impair Mr Garrett's ability to make a difference as an MP.
Mr Hide said Mr Garrett made a terrible mistake, that caused significant hurt, but the matter had been dealt with by the courts.
He also revealed on the programme that he was convicted for being drunk at Heathrow airport when he was a young man.