In his speech to the party faithful, Seymour also set out his list of proposals for the first 100 days of a potential National – Act Government – and a warning to National that it would have to "learn to share" more in a two-party government than it had in the past.
He said Act's hopes of a two-party government were now in reach.
"That doesn't mean we're there, just that we're closer than we've been before. Not only do we have a strong chance of the Government changing, we have every chance of being an indispensable part of the new one."
In recent polls, Act and National have been on level pegging or just ahead of the Labour-Greens combination – and in some polls Te Pāti Māori has been the kingmaker.
Seymour said a National-Act Government would be different to the arrangements National had known in the past, when it worked with a combination of Act, United Future and the Māori Party.
"We won't allow National to lazily roll over Labour's policies like it has in governments gone by. National will need to learn how to share with a larger and more powerful coalition partner than it's had before."
"There's not point beating Labour just to babysit their policies; their bad ideas need to go, and voters deserve to know they're going."
His 100-day wishlist included reversals of Three Waters, the Māori Health Authority, the Public Interest Journalism Fund, the Zero Carbon Act, and Fair Pay Agreements among others.
It also wanted to overturn the ban on oil and gas exploration, and repeal the provision for Oranga Tamariki requiring it to consider iwi as the first preference for placing a child.
The 100-day plan also calls to reinstate 90-day trials, charter schools and the three strikes policy – all policies which were put in place under the previous National Government, and which it still supports.
National Party leader Christopher Luxon has committed to bringing back charter schools, recently visiting one in London.
Act's other 100 day proposals include scrapping the bright line test and reinstating interest deductibility for property investors, and putting in place a flatter tax structure with only two brackets.
Seymour said previous MMP governments had consisted of at least three partners – other than the current Labour majority Government.
"I predict that, with everything we are being put through right now, the New Zealand people won't trust one party with government for a generation, at least."
And he set out the list he would be taking to National in any post-election talks with his expectations for the first 100 days of a new government.
He said Act would expect National to do more than simply carry over Labour's reforms, saying that was what happened in the past.
"This is why I don't vote National. They've been in power for 47 of the last 72 years. If the National Party were the solution to any problem, we wouldn't have that problem now."
Although Christopher Luxon's leadership meant Act's polling was now lower than it was in the aftermath of the 2020 election, Seymour said the party was in very good health – financially, in its membership, in the numbers seeking to be candidates, and in the polls.
Yesterday Seymour also announced a proposal for Inland Revenue to go after gangs' income with the powers it has to compel people and organisations to hand over financial information on their incomes – regardless of the source of the income.
Seymour said forcing the gangs to pay tax on income from illegal activity could be just as effective as police action.
Seymour will speak at the party's conference at Wellington at about 2.30pm.
The guest speaker is Professor Elizabeth Rata, from Auckland University.
Party president Tim Jago and MPs Karen Chhour, Nicole McKee, Brooke van Velden will also speak.
The conference is a low-frills two-hour affair, but the party faithful will also meet tonight for a dinner to mark the 25th anniversary since Act first got into Parliament.
That event was delayed by a year because of Covid-19 lockdowns.
