Unions New South Wales says 20 per cent of Coalition supporters would vote against the Howard government if an election was held tomorrow.
The new laws were introduced on Monday and and have removed unfair dismissal provisions for companies with less than 100 employees.
Unions NSW commissioned a national survey which shows one-in-five Coalition voters are angered by the new Industrial Relations laws and would change their vote at the next federal election.
Secretary John Robertson says Australians are changing their vote because they think family life is being compromised by the federal government.
"If employers continue to use the extremes contained in these industrial relations changes, and we continue to run a very strategic campaign, and Labor gets focused on industrial relations, I think we could see a swing of those sorts of proportions at the next election."