Moore began his parliamentary career when elected as the MP for Eden in 1972, becoming the youngest MP at 23 years of age, where he served for one term before being defeated in the . Following the announcement of Norman Douglas' retirement from the safe seat there was much speculation that Moore would seek the Auckland Central nomination. The media considered Moore one of the most able backbenchers in the Labour Party, however Moore decided to stand in the marginal Eden seat once again. Once again Moore was offered a safer seat when he was approached to replace cabinet minister Hugh Watt in , Watt encouraged him and even offered to campaign on Moore's behalf. However Moore declined wishing to remain in Eden to show confidence in Labour and its new leader Bill Rowling's ability to win the election.