Rodney Hide survived moves to oust him as Act Party leader last month after Prime Minister John Key privately indicated National's deal with Act would be off if the minister were dumped.

And it is believed that at the height of controversies in the two support parties - the Act leadership and the Maori Party's turmoil over MP Hone Harawira - Mr Key briefly considered a snap election to gain National an outright majority.

Act founder Sir Roger Douglas, with deputy leader and Consumer Affairs Minister Heather Roy, is understood to have led moves in the party against Mr Hide during the controversy over the international travel costs of his partner.

The Act board was told the caucus had issues over the leadership, and a special caucus meeting was called for November 22.

Mr Key is understood to have learned about the moves against Mr Hide shortly before that - between his return from Apec in Singapore and his trip to Trinidad for the Commonwealth summit.

He told Mrs Roy that if Mr Hide were removed from the leadership, her own ministerial position would be in jeopardy.

Mr Key has long ruled out having Sir Roger as a minister.

National's confidence and supply agreement with Act, including the two ministerial positions, was negotiated between Mr Key and Mr Hide.

The Act caucus meeting was held, but the push to oust Mr Hide had fizzled by then and no vote was taken.

Shortly after the caucus meeting, Mr Hide told Radio New Zealand he had asked the caucus to "review" his leadership and there had been a discussion about it.

Two incidents provided the catalyst for the moves against Mr Hide.

The former perk-buster had got around a directive from Mr Key against using ministerial budgets to take partners on overseas ministerial trips by using the separate parliamentary travel discount for MPs and their spouses.

And he was sprung over criticism of Mr Key he made at an Act fundraising breakfast in Christchurch, when he said the PM "doesn't do anything".

Mr Hide subsequently made abject apologies on both counts.

The Epsom MP is Minister of Local Government, Minister for Regulatory Reform, and Associate Commerce Minister.

Sir Roger, aged 72, has publicly criticised Mr Hide for being too populist. The former Labour finance minister returned to Parliament a year ago after retiring from Parliament in 1990.

National has 58 MPs in the 122-member Parliament. It has the support of Act (5), the Maori Party (5) and United Future (1). If its relationship with Act had ended, it would still have had enough support to govern.