The deal between the National and ACT parties is likely to stretch further than Epsom, with ACT potentially willing to step aside in some marginal seats to help National win.
In an apparent agreement between the National and ACT parties over the Epsom seat, National's candidate Paul Goldsmith plans to target the party vote in the November general election while ACT's John Banks says he will be working the electorate vote.
There are understood to be informal discussions about possible co-operation elsewhere.
In seats National wants to wrest from Labour, or retain in the face of a strong Labour challenge, ACT would be willing not to stand candidates, and maximise National's vote.
But Labour Party candidates in potential target seats say that would not hurt their chances.
Former Labour Party president Andrew Little, who will contest the marginal National seat of New Plymouth, says he is targetting thousands of voters who were disillusioned with Labour in 2008.
And Clayton Cosgrove, who holds Waimakariri for Labour with a 390-vote majority, is confident voters will see any deal as a jack-up.