HSU NSW secretary Gerard Hayes on Tuesday said affiliation to NSW Labor no longer "represents value for money" as the party is unlikely to revive its electoral fortunes in the near future.

Mr Hayes and AWU secretary Daniel Walton earlier this month leaked internal party polling which revealed voters had abandoned NSW Labor in droves.

It predicted that if an election was held now, Labor's primary vote would be 23.9 per cent - a drop of 8.4 percentage points since the 2019 state election.

Taking into consideration a redistribution of seats, the swing would see Labor lose 12 seats, including Ms McKay's seat of Strathfield.

Ms McKay at the time said the leaking of the poll was tantamount to a "coward punch" and labelled Mr Hayes and Mr Walton "faceless men".

A meeting of the HSU council on Tuesday resulted in the disaffiliation of the union from NSW Labor, with Mr Hayes abstaining from the vote.

"We felt it was in the public interest to release this polling to the media to spark the honest, transparent conversation needed to trigger a revival of Labor's fortunes," Mr Hayes said in a statement.

"Unfortunately the leader of NSW Labor responded with personal insults.

"We therefore have little faith that Labor is likely to improve its performance any time soon."

Electoral records show the HSU made more than $200,000 in political donations in 2019/20, all of which went to either NSW Labor or Country Labor.

Ms McKay declined to comment. NSW Labor has been approached for comment.

Australian Associated Press