Part of this was down to Seymour's strong personal performance, part of it was the surprising discipline of his new caucus, and part of it was the formidable back office team Seymour assembled, led largely by ex-National staffers with something to prove.
But this year, with National under new leadership, disaffected centre-right voters are returning home. In the February Newshub poll, Act's vote had been cut in half.
Seemingly in a panic, Act appears to have ditched its previous strategy and is back to focusing on its base. We saw that this week with the traditional play for a party tanking in the polls - the race card.
Seymour's cynical "bottom line" of a referendum on Māori co-governance, something Act had no problem with in Treaty settlements when it was in government but now finds itself deeply opposed to in Opposition, brought to mind the lowest point of his career - deliberately tweeting priority access vaccination codes for Māori to sabotage the vaccination rollout.
The political strategy behind this move makes some sense on paper. Have the junior coalition partner focus on the right-wing base, leaving National under Christopher Luxon to focus on winning centre-ground voters off Labour on issues like the cost of living.
In reality, though, the actions of a junior coalition partner reflect on the major party. That's because voters know in an MMP environment, the policies of minor parties can be taken up after the negotiations.
That's why Luxon had to spend much of his media interviews this week dancing around whether he would rule Act's race referendum in or out. Luxon will be keenly aware that in 2022 the middle-ground voters who decide elections react badly to this kind of race-baiting. It's why he's hardly ever mentioned the He Puapua conspiracy theory which was such a significant part of Judith Collins' leadership.
This dynamic could be a problem in economics as well. If you look under the hood, Act's economic policies are decidedly outside the mainstream. From putting interest back on student loans, to cutting the number of sick leave days available for workers, to stopping minimum wage rises, to abolishing Working for Families, Act's policy platform is full of things that would hurt lower and middle-income voters in their hip pockets.
The second problem with Act's base-first strategy is that on current polling, Te Pāti Māori will be the kingmakers at the election. Act running a sustained anti-Māori campaign will only make it harder for Luxon to coax Te Pāti Māori into forming a centre-right government.
So by playing to its base, all Act is doing is making it harder for Luxon to win over the centre, and harder to build the type of winning coalition that MMP politics demands.
There's clearly a smarter way forward for Act- just a few weeks ago it won widespread plaudits for its carbon dividend policy. A smart, credible way of tackling both climate change and the cost of living, through a small government lens.
Highlighting that sort of approach, instead of the old Don Brash playbook, seems to be a much more viable strategy for Act - not only if it wants to arrest its polling slide, but also if it wants to form a government.
● Hayden Munro was the campaign manager for Labour's successful 2020 election win. He now works in corporate PR for Wellington-based firm Capital Communications and Government Relations.
