He said the union was considering a donation to Internet-Mana, but "considering Kim Dotcom's on board, I'm not sure they will be lacking any funds".
Maritime Union national secretary Joe Fleetwood said the union would probably give $10,000 to Labour, but the figure would not be confirmed until the end of the week.
SFWU national secretary John Ryall said the union was also asking members if they wanted to be more active in trying to change the Government.
He said that might entail mobilising members not only to vote, but to vote for change.
The Dairy Workers Union has yet to make a decision on donations. Last election, it gave $27,200 to Labour.
The Meat Workers and Related Trades Union, also an affiliate of Labour, has yet to confirm donations. Last election, it gave $18,000 to Labour.
"We support a number of political parties - Labour, Mana, the Greens," said national secretary Graham Cooke.
"We support any party that supports working people that are not getting a fair share of the cake."
He said the union could give donations to more than one party.
A spokesman for FIRST union said it would not be making donations.
"But we're telling our members we want a change in Government, and loosely saying Labour, Greens and Mana are the ones we would endorse for workers' rights, in general."
The Public Service Association, the country's largest union with 58,000 members, is non-partisan and does not donate.
However, it is participating in the Council of Trade Unions' Get Out And Vote campaign.
CTU president Helen Kelly said it did not donate but might highlight specific policies.
A number of non-affiliated unions, including the NZEI and PPTA teachers' groups, do not support particular parties or donate.
A PPTA spokeswoman said: "Our members are teachers and they vote all over the political spectrum."
Donations
• Engineering, Printing and Manufacturing Union
$60,000 - Labour
$15,000 - Greens
• Service and Food Workers Union
$22,000 - Labour
$6000 - Greens
• Maritime Union
$10,000 - Labour (not finalised)
• Rail and Maritime Transport Union
$10,000 - Labour and Greens (not finalised).