Shadow treasurer Chris Bowen says the Labor Party will not take a "Buffett rule" to crack down on wealthy tax avoiders to the next election, setting up a showdown with elements of his party who believe such a policy would help counter the rise of populist parties like One Nation.

In a decision that puts Mr Bowen and Opposition Leader Bill Shorten at odds with the Left of Labor, Mr Bowen ruled out supporting the push, revealed by Fairfax Media on Wednesday.

Under the plan, adopted by the national Left faction over the weekend, the highest-income earners in Australia would be forced to pay a mandated minimum rate of tax - most likely 35 per cent for those earning $300,000 or more a year - discouraging the pursuit of tax loopholes and aggressive tax planning.

"This approach isn't the best way to address inequalities in the system. A Buffett rule won't be something we take to the next election," Mr Bowen said.