Auckland Mayor Phil Goff has come out in support of Efeso Collins as his replacement

Goff had previously decided not to support any of the mayoral hopefuls - but now says Collins is committed to a lot of the same things he believes in.

It follows endorsements by both the Labour and Green parties.

In the past 10 days, Collins' poll ratings in the monthly Ratepayers' Alliance-Curia poll dropped by five points to 22 percent.

The withdrawal from the race of restaurateur Leo Molloy, has also reduced the field of major opponents from three - to two.