WELLINGTON, New Zealand (AP) — New Zealand's political opposition leader said Thursday he's leaving the top job because he doesn't think he has the support of his colleagues ahead of national elections next year.

David Shearer led the center-left Labour Party for 20 months but appeared to struggle at times in the spotlight. Opinion polls indicate he never gained much support among New Zealanders as preferred prime minister.

Prime Minister John Key, on the other hand, continues to enjoy high levels of support after first taking office in 2008.

Shearer will remain in Parliament as a lawmaker. He hasn't yet said if he'll contest his seat next year.

In a statement, he said it was time for a change.

"There was no letter, there was no ultimatum, there was no vote," he said. "But from the soundings I have taken from colleagues, I realize I no longer enjoy the confidence of a number of my caucus colleagues."

Shearer said he came into politics to make a difference and, "I believe I have done that."

The Labour Party plans to pick a replacement in the coming weeks.

Among those expected to vie for the role are deputy leader Grant Robertson and associate finance spokesman David Cunliffe.

Shearer was elected to Parliament in 2009. He previously worked for the United Nations and was named "New Zealander of the Year" by the New Zealand Herald newspaper in 1993 for his work in Somalia.