A One News-Colmar Brunton Poll on the electorate vote in Epsom suggests a deal between the National and ACT parties may have backfired.
National's leader John Key held a cafe meeting with ACT candidate John Banks last Friday to send a signal to National supporters to give their electorate vote to Mr Banks.
Securing the seat is ACT's best chance of making it back into Parliament and would also give National a potential partner in government.
However, the poll shows National's candidate Paul Goldsmith on 41% support, enough to win the seat, and John Banks trailing on 30%.
A separate nationwide poll of National supporters found only 29% supported the deal between ACT and National and 55% opposed it.
The Epsom poll surveyed 517 voters and has a margin of error of 4.4%.