Waka Kotahi cannot say yet if the main road from Thames to Tairua on the Coromandel peninsula will be fixed by the end of the year.
State Highway 25A crosses the region from Kopu to Hikuai, but a huge area of the road has been swept away in a major slip following destructive amounts of rain.
The road was showing big cracks in the weeks before the recent severe weather event.
Waka Kotahi spokesperson Cara Lauder told Checkpoint the size of the slip was increasing and there was now a 150m gap in the road.
"It's definitely growing in size, even since yesterday. So that was only this morning. We lost about 60 or 70m of the road today additional to what was already gone. So, it's very large," she said.
Lauder could not say if the road would be fixed by Christmas.
"We had some specialist contractors out there before it went and they would give us the great ideas. We really need to get them back to give us a bit more of a punt now that we've lost so much more...
"If we have to build a massive bridge across it though, if it does get to that kind of scale, those things do take a bit longer," she said.
The road is the key link to towns like Whangamata, Pauanui, Tairua, Hot Water Beach and Hahei.