"They're saying to their workmates and neighbours that if you want to increase your wages, to have your kids stay in New Zealand and not go to Australia, then you need to vote for a Labour-led government.
"Our 23,000 members won't win the election, so we've encouraged members to get involved in enrolling their own communities in the streets and blocks where they live."
The primary target is South Auckland - four of the biggest turnout drops in 2008 came in Manurewa, Manukau East, Papakura and Mangere.
The Council of Trade Unions is working with unions in Australia to ensure that people eligible to vote in the election are enrolled.
Although the CTU, the Engineering, Print and Manufacturing Union and others do not endorse a specific party, the subtext of their messages is clear.
CTU secretary Peter Conway said publications aimed at its 360,000 members included a graphic comparing National and Labour/Green policies.
"It's a factual representation, but clearly what it implies is if you want a worker-friendly Government, you need to change the Government."
The CTU has also developed a "scratch and lose" card to highlight what might happen under a National-Act Government.
"And we've got a surprise hidden policy in there - GST to 20 per cent. We know John Key would say he wouldn't do that, but that's what he said last time," Mr Conway said, referring to Mr Key's pre-election statement in 2008 that he would not raise GST.
The CTU is one of many unions that registered with the Electoral Commission in case its regular mail-outs could be interpreted as election advertising.
None of the unions said they would spend anything close to the $300,000 limit.
Most of them also support keeping MMP.
Like the CTU, the Public Service Association has commissioned a third party to develop advertisements.
PSA national secretary Brenda Pilott said their message was the importance of public services; the PSA was spending about $200,000 on a series of billboards and advertising, including online videos, to push its message.
"We think very carefully before we spend money, but it's central to promote our members and go in to bat for them when the work they do is being questioned."
One billboard reads: "Don't worry, skilled service workers will be re-employed where they're most wanted", sitting next to a picture of Australia.
The PSA is also hosting political "speed-dating" sessions where party spokespeople can be grilled by the audience on a range of election topics.
Robert Reid, national secretary of the FIRST union (formerly the National Distribution Union) said it was recommending members vote Labour, the Greens or Mana.
The rules
Old rules:
* Promoters listed with the Electoral Commission can spend up to $4000 to influence a vote for or against a candidate, or up to $120,000 on a party in an election year.
* Endorsement or support of a particular candidate or party requires their specific approval and must also be included in their spending cap.
New rules:
* Promoters can spend up to $300,000 on election and MMP referendum advertising during the regulated period (Aug 26 to Nov 25).
* Election advertising is defined as encouraging or persuading voters to vote, or not to vote, for a candidate or party.
