Act expects to ink a new coalition agreement with the National Party by the end of the weekend, which may include a ministerial role, MP John Banks says.
Mr Banks, former Act MP John Boscawen and party president Chris Simmons emerged from coalition talks with Prime Minister John Key early this afternoon with the outline of an agreement they will take to their board tonight.
Mr Banks said the discussions went "very constructively, very well, with quite a lot of momentum".
"We now go back to the Act Party board with the matters that were narrated."
He was hopeful of going back to Mr Key by the end of the week and have the deal inked by the end of the weekend.
"He wants to do things sooner rather than later."
Mr Banks said talks today had seen negotiation of "some things that are important to the Act Party values... around choice responsibility and private enterprise".
He confirmed there was talk about him potentially taking a ministerial portfolio.
"I think I can make a contribution in Cabinet but we haven't nailed down anything around that yet."
However he said he would be interested in "a ministerial platform around investment, growth jobs and success for the tradeable sector".
While Act only had a single MP rather than the five it had in 2008, Mr Boscawen said Act's bargaining power was not substantially diminished.
"That MP makes sure the Government can pass its legislation."
Mr Banks said Act stood to make policy gains in excess of what might be expected for a party with just one MP.
"I think you're going to be very surprised, the gains we've been able to negotiate and it's not at all about me it's about the legacy of trust and goodwill between the Prime Minister and the Act party and in particular John Boscawen over the last three years."
United Future leader Peter Dunne also continued his discussions with National today, and said the talks had been "pretty positive".
"There are still some nuts and bolts to sort through, but it's making good progress."
He would not comment on how long it would take to finalise the details of the agreement, or what specific areas he was looking for concessions in.