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Mr Powell was commenting on the fallout from the Employment Relations Amendment Bill, which the Government has been forced to abandon.
Mr Banks is resigning his Epsom seat and leaves Parliament tomorrow, having been found guilty of filing a false electoral return.
Prime Minister John Key said National was likely to make the employment law change part of its election campaign, since it cannot pass the Bill without Mr Banks.
Unions have fought the changes which they said removed rights to tea breaks, undermined collective bargaining by allowing employers to walk from talks, and reduced protection for vulnerable workers.
Mr Powell, of the Association of Salaried Medical Specialists, said the changes would have created an ''adversarial'' employment relations environment in health.
National collective agreements would have been less likely.
These worked well in health, as boards were increasingly linked, so it made sense for staff to share conditions around the country.
New Zealand was hugely reliant on foreign doctors, and their rights as new employees in an unfamiliar country would have been reduced.
''It's so intriguing to see John Banks as a working class hero,'' Mr Powell said.
Service and Food Workers Union national secretary John Ryall was ''overjoyed'' the Government had been forced to abandon efforts to reduce workers' rights.
He was particularly pleased Part 6A of the existing Act covering vulnerable workers would be unchanged.
Mr Ryall said bargaining entitlements were already limited, and the Bill worsened the situation. It favoured employers and would put downward pressure on wages.
CrestClean managing director Grant McLauchlan, of Dunedin, who has pushed for reform of Part 6A, which protects vulnerable workers, was also pleased the Bill had been dropped, as it had not addressed the main issue.
It was a ''great result'', and he hoped the next Government had a strong mandate to make ''pragmatic and appropriate changes'' to the ''broken'' Part 6A.
New employers were not told whether employees wanted to transfer to their company until the day before a new contract started, which the Bill would not have addressed. He denied the industry was trying to lower the wages of vulnerable workers.
''How can you pay someone cheaper - they're all on the minimum wage [already]. The people that we take over, how can we ever pay them less? ''The people we take over unfortunately are the people that have been poorly managed by their existing company.''
The Bill exempted employers with 19 or fewer employees from Part 6A, but that only helped the ''small end of town'', Mr McLauchlan said.
Otago-Southland Employers Association managing solicitor Diana Hudson said the changes had been a long time coming, and it was disappointing they would not go ahead.
The law governing tea breaks was far too prescriptive, and did not work for many employers, Ms Hudson said.
''This is not about removing entitlements - it's about making the entitlements more flexible.''
Part 6A was difficult to work with in its present form, and the proposed changes would have ''provided more clarity'', she said.
University of Otago politics lecturer Dr Bryce Edwards said it was embarrassing for National to have to abandon part of its legislative programme.
He did not think employment relations were set to be a big election issue.
''I just don't think it's going to be a particularly sexy issue for Labour to campaign on.''
Likewise, National was unlikely to push the issue much in its campaign.
The changes were a nod to National's support base, rather than a big vote winner, Dr Edwards said.
He believed the unions had exaggerated the importance of the changes but it was their role to do so.