However, it is understood Jackson broke the bad news to Maori Party President Tukoroirangi Morgan yesterday.
Sources close to Jackson said part of the reason for his move was concern that he did not have full support from within the Maori Party and that Labour enticed him with assurances of backing for a good list placing rather than standing against Labour's Peeni Henare for the Maori Party in Tamaki Makaurau.
Davis confirmed he had been told but he was yet to speak to Jackson. He admitted he was surprised when he was first told, but thought it was great news.
"He's got profile, he's got charisma. He's got such pro-Maori ideas. I think it's fantastic. And he's a leftie. I'm really quite excited by it."
Davis might have to be on the list to return if Mana leader Hone Harawira's attempt to reclaim the Tamaki Makaurau electorate is successful. The Maori Party is not standing in Te Tai Tokerau this election as part of a deal with Mana.
Davis said he would not be concerned if Jackson was above him. "It's not about me. It's about Maoridom and changing the Government."
"It's great news. I think we need to bring in outstanding candidates and they need to be assured of a decent place. This is the way we'll show Maoridom we are serious about Maori issues, by bringing in more Maori on the list."
A high list ranking for Jackson could upset other Labour MPs and Maori candidates however.
The party is aiming to get at least 50 per cent women in its caucus after this year's election, which means there are very few list places for men.
As well as Labour leader Andrew Little, Trevor Mallard, who is hoping to be Speaker if Labour is in Government, and David Parker are reliant on the list to return to Parliament. Promising Maori candidates such as Willow-Jean Prime are also likely to need the list to get into Parliament.