ACT is a party of ideas. Not even its most fervent supporter could imagine it will ever be a dominant political force. But it can exert an influence by championing policies that are picked up by the major parties. National, Act's long-standing partner, is the obvious recipient of ideas hammered from the anvil of free enterprise, individual freedom and low taxes. And therein lies the flaw in Act's co-operation agreement with the Labour Party and increasingly tart comments about National shift to the centre under John Key's leadership.

It is easy to see the advantage of this agreement from Labour's viewpoint. The Therapeutic Products and Medicines Bill has had to be put on hold for want of the two votes needed for its passage into law. Act may supply those after taking another look at the legislation. Quite conceivably, this will not be the last time Labour is inconvenienced in this manner, and Act could again find its votes coveted, whatever the philosophical differences.

It is difficult, however, to see this arrangement being of any real benefit to Act. Rodney Hide, the party leader, justifies it by saying Act is now prepared to work with either of the main parties to be "a positive force" in Parliament, not just a party of Opposition. "We have not changed our philosophy or our principles," he told the Wellington regional conference.

Even in terms of the therapeutics bill, it is hard to see how this can be so. This legislation, as party founder, Sir Roger Douglas, pointed out, is all about increased government controls. Regulation is still regulation, even if the target is greenish-tinged products. As such, the bill should, in Act eyes, be a matter of instant anathema.

Cosying up to Labour in this way risks diminishing Mr Hide in Act supporters' eyes. More, perhaps, than the followers of any other party, many of them place purity of policy above pragmatism. The only saving grace for Mr Hide is that National's centrist drift leaves these people with no obvious option. However, the new approach also risks antagonising their traditional allies. National's leaders, seeing Act willing to provide the final drops of oil to lubricate Labour policies, may feel far less inclined to entertain its policies when they hold power. If so, Act will cease to matter as a political influence.

That is, of course, if it has not already stopped mattering as a political entity. Act's two seats are the product of National supporters' strategic voting for Mr Hide in Epsom. Voters in that electorate gave him 42.6 per cent of their candidate votes, against 33.9 per cent for National's Richard Worth. But Act won just 3.4 per cent of the party vote, and National 58.5 per cent. Whatever Mr Hide's performance as an electorate MP, many National supporters must question whether Act is worth saving. In the latest Herald-Digipoll survey, it attracted just 0.6 per cent support. Act's future will surely lie in the hands of those Epsom voters.

As much as Mr Hide may try to rationalise his approach, it is difficult to see it as other than an act of desperation. He has acknowledged that his perk-busting activity and campaigns against individual ministers won him little kudos. Now, having cast around for an alternative, he has settled on something that smacks strongly of self-destruction.

Richard Prebble, a former leader, said National's vacating of the free enterprise side of the political spectrum meant Act would be chasing 20 per cent of the party vote at the next election. That is pipe dreaming. Act has the potential to remain a credible voting option, but only if it stays true to itself and its principles.