French Polynesia's Tahoeraa Huiraatira says it is surprised that the leader of the small Te Ara Tia Party, Frank Falletta, has decided that he will now back the Tahoeraa's pro-autonomy rival.
Mr Falletta has told Tahiti News that a voice told him during the night that he should support the A Tia Porinetia.
Campaigning is in its last days as voters prepare for the second round of the election of a new territorial assembly.
The Tahoeraa dominated the first round and some of the eliminated parties have suggested to their supporters who to vote for in the run-off.
It says Mr Falletta, who is a high-profile businessman, had talked to the Tahoeraa leader, seeking a ministerial position.
Mr Falletta has told Tahiti-infos that if the A Tia Porinetia wins, he will quit his job and spend a year as an unpaid inter-ministerial delegate to help promote investments.