Early political career

Halbert stood as a list-only candidate for Labour in the 2014 general election. His party list ranking of 48 was too low to win a seat.^[8] In the 2017 general election, he sought the Labour Party selection for the Auckland Central seat, losing to Helen White. He instead contested the Northcote electorate; he neither won the electorate nor won a list seat on his party list ranking of 51. In 2018, after the resignation of National MP Jonathan Coleman, Halbert again contested the Northcote by-election as Labour's candidate, having been chosen for the candidacy over Paul McGreal and Auckland Councillor Richard Hills.^[7][9] He was defeated by National's Dan Bidois.

First term, 2020–2023

In the 2020 general election, Halbert was again ranked 51st on the Labour party list and contested the Northcote electorate. This time, Halbert won the seat from incumbent National MP Dan Bidois by 2534 votes.^[10][6]

Halbert has for years campaigned on improving public transport, as congestion in the Northcote electorate—located at the northern landing of the Auckland Harbour Bridge—is a defining issue for many voters.^[11] For the 2020 campaign, he also campaigned in support of local businesses and advocated for improved access to mental health services.^[6] His father died of lung cancer on election day.^[12]

Halbert faced criticism in both the 2020 and 2023 election campaigns for misleading advertising. In 2020, he published a flyer in which Labour claimed, “We’ve built over 600 houses for our growing Northcote family.” A complaint to the Advertising Standards Authority noted that only 74 homes had been built. Labour apologised for the flyer and pulled it from stalls. In 2023, another flyer from Halbert celebrates “1700 new warm, dry homes as part of the Northcote Development”, but these homes were not scheduled for completion until 2026. This flyer also faced a complaint to the Advertising Standards Authority, but the Authority dismissed it. An article by Tova O'Brien criticised the flyer for being unclear which points were prior actions by Labour and which were promises if re-elected. Halbert also stated on Facebook that the National Party plans to decrease sick leave to five days per year, which is not its policy.^[13][14]

In 21 September 2023, Halbert was the subject of bullying allegations by several former staff, who claimed he was manipulative, scheming, narcissistic, and intimidated them. Labour whips were first alerted to the allegations by a bullying and harassment coach in August 2022 but no action was taken since staff wished to remain anonymous. In response to the bullying allegations, Halbert said that he had a good relationship with parliamentary and other staff, while acknowledging he had encountered employment issues but had done his best to resolve them professionally. Halbert urged disaffected staff members to engage with Parliament's complaint process.^[15] During an election debate in Northcote, Halbert denied the bullying allegations and claimed he had not received any complaints when confronted by Newshub journalists.^[16]

Second term, 2024–present

During the 2023 New Zealand general election, Halbert was unseated by National candidate Bidois, who won by a margin of 9,270 votes.^[17]

In early February 2024, the simultaneous resignations of both Labour MPs Kelvin Davis and Rino Tirikatene allowed Halbert and Tracey McLellan to reenter Parliament on the Labour Party list.^[18] During a shadow cabinet reshuffle triggered by the resignation of Grant Robertson, Halbert assumed the Auckland Issues and newly-created Rainbow Issues portfolios.^[18][19]

In response to Destiny Church's protest against a Drag Queen Story Hour event in Gisborne in late March 2024, Halbert described the church's behaviour as "very disappointing." While Halbert supported the right to protest, he condemned what he regarded as "vicious discrimination against young people and their families." He also criticised the National-led coalition government's plan to remove sexuality guidelines from schools. Halbert's claim that the National-led government wanted to remove hate speech laws was disputed by Justice Minister Paul Goldsmith, who said that the Government had no plans to remove hate speech protections in law but opposed Labour's proposed hate speech legislation on the grounds that they would have undermined free speech.^[20]