New Zealander of the Year, Dr Lance O'Sullivan, Dame Tariana Turia, actor Rawiri Paratene and Tame Iti are among those who have posted videos of support to the Mana Party Facebook page.
Harawira has released the poll on the eve of another by Maori Television which also shows he is trailing Davis by a significant margin.
He said the poll showed tactical voting appealed to those in the electorate on the basis it would bring into Parliament two MPs from the Far North who had contested Te Tai Tokerau.
"That information more accurately reflects what we're seeing in the north. We know we've got a battle on our hands, but we also know that the '2 for 1' campaign has been extremely effective and has gone viral on social media.
"Voters can see that they can get two MPs by just voting for one, and they feel good that they can exercise that option."
The Curia poll showed Davis and Harawira were equally well recognised by voters, who ranked the most important issues as housing, poverty, education and health.
It also shows that the deal between the Maori Party and Mana Party has worked, with 67 per cent of Maori Party voters opting for Harawira.
"I'd be happy to work with Kelvin, and anybody else, to get back the foreshore and seabed that his party stole, to feed the kids and house the whanau that his party abandoned when they privatised health, social welfare and housing and to create community work for the unemployed in the north.
"I bear no ill will towards Kelvin. I simply want to rebuild our world."
For Harawira, the key part of the Curia poll is what happened when voters were asked if they would be more likely to vote for Harawira knowing that Davis was assured a seat on Labour's list.
The poll showed 38 per cent of voters were more likely to vote for Harawira on the basis it would give Te Tai Tokerau two MPs.
Davis unleashed a stinging attack on Harawira, saying Te Tai Tokerau should vote for "quality not quantity".
"He ruined the Maori Party, he ruined the Mana Party and he's ruined Internet-Mana and as a result no other party will have him. If he's in Parliament, he won't be effective. It's a wasted vote.
"I want the mandate of my people."
Davis said the electorate would still get its second MP - just not yet.
He said he intended to step aside from the electorate after one or two terms and go on the list to bring someone new into the electorate which he predicted would bring strong Maori candidates from across the political spectrum.
"When I take my chances on the list they'll want the electorate seat so they'll jump in on the Labour ticket."
Harawira said the poll carried out by polling company Curia - and provided to him by a supporter - shows that the gap is closer and better reflects the race to win Te Tai Tokerau than an upcoming Maori Television poll.
Harawira said he released the poll because he disputed the way in which the upcoming Maori Television poll was done - over a longer time period and focused on landlines.
He said the Curia poll, showing a narrower gap, was done at the beginning of the month and sampled landlines and mobile phones.
