NZ First Leader Winston Peters is taking the fight to Colin Craig by refusing to rule out standing against the Conservative Party Leader in East Coast Bays.
As NZ First marks its 21st anniversary at its birthplace, Auckland's Alexandra Park, Mr Peters also indicated he is set to announce a tax on foreign investment.
About 150 NZ First members are gathered for the conference while across town Mr Craig's party was winding up its own annual meeting.
Mr Peters again claimed Mr Craig had plagiarised much of NZ First's policies, but he said the Conservatives didn't have "the commitment" to make those policies happen.
Mr Craig is standing in East Coast Bays where he stands little chance of winning unless National's incumbent, Foreign Minister Murray McCully stands aside.