Multi-sport athlete Richard Ussher says the annual Coast to Coast race is shrinking in popularity and needs a management overhaul to improve it.
The gruelling race was founded by Robin Judkins 31 years ago and is due to be held on Friday.
It traverses the South Island from Kumara Beach on the Tasman Sea to Sumner Beach on the Pacific Ocean.
On Monday, Ussher released a 10-point plan highlighting how to improve the race, including the resignation of Mr Judkins.
He told Radio New Zealand on Tuesday that the plan was not meant as a personal attack on Mr Judkins, but he stands by his comment that new management could revitalise the race.
Ussher said he has had support from other athletes about the race, which costs more than $1000 to enter - a price that some have told him is off-putting.
While endurance racing is growing in popularity around the world, the Coast to Coast is not, he said.