The DA and EFF must be taught a powerful lesson, SA communist party general secretary Blade Nzimande said on Saturday.
"Use May 7 to teach the Democratic Alliance a powerful lesson. They say they are for jobs but were against farm workers in the Western Cape," he told the National Union of Minewokers' national shop stewards' council conference in Boksburg, east of Johannesburg.
He described the DA as a party of "political labour brokers".
"When the DA marches to Cosatu house and Luthuli house, [the party] is black but in Parliament it is white."
He described the Economic Freedom Fighters as a party full of "corrupt tenderpreneurs".
"If you owe the SA Revenue Services R16 million, do you know how many millions you've chowed? They chowed more than R100 million," said Nzimande .
"Some people wear expensive watches and clothes but have never worked a day in their lives."
According to court documents, EFF leader Julius Malema owed R16 million plus interest after failing to submit tax returns between 2006 and 2010.
In 2010, the Sars contacted Malema about his failure to submit tax returns.
It took Malema 18 months, after many attempts by the Sars, to file his outstanding returns.
Malema also failed to register the Ratanang Trust for tax purposes, and Sars had to do this on his behalf.
His legal team asked the High Court in Pretoria in February to postpone his sequestration case. Sars opposed it.