Bridges is on just 5 per cent and is neck-and-neck with Judith Collins.
Ardern's 51 per cent on the rating in the preferred Prime Minister ranking was up 7 percentage points.
The poll was taken after the March 15 terror attacks.
Speaking to 1 News, Ardern said: "I just know I have a job to do on behalf of New Zealand and I'm doing it".
Bridges said Ardern had fronted on behalf of New Zealand and "had done a good job".
Asked about his low personal polling, Bridges said what matters was the party vote.
"I'm pleased with where I'm at – but I know we have work to do. I'm pleased to be leading a party that is in the 40s."
He said his low polling was "a function of name recognition".
He did not directly answer questions about being on the same polling as Collins, only saying National "had a bunch of great MPs".
As for the smaller parties, New Zealand First – although up one percentage point on the last poll – was once again under the 5 per cent threshold with 4 per cent support in the poll.
The Greens were steady at 6 per cent and Act steady at 1 per cent.
The polling numbers:
Labour – 48 per cent (up 3 percentage points)
National – 40 per cent (down 2 percentage points)
Green Party – 6 per cent (steady)
NZ First – 4 (up 1 percentage point)
Today's poll comes after the March 15 terror attacks in Christchurch.
Ardern's response to the attacks was praised by many, including celebrities and politicians around the world.
At one point, a photo of Ardern embracing a woman appeared in lights on the side of the world's tallest building, the Burj Khalifa, in Dubai.
Just three weeks after the attack, the Government had passed new gun laws which ban the same semi-automatics weapons the gunman used in the attack.
Asked about New Zealand's economic outlook, 37 per cent of people were optimistic and 36 per cent were pessimistic.
