[8] In the 2017 general election, he sought the Labour Party selection for the Auckland Central seat, losing to Helen White.

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.

[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.

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.

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.

[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.