South African opposition party the Economic Freedom Fighters has written to the speaker of parliament seeking to block lawmakers from meeting on Wednesday to vote on the next stage of the budget process.

South Africa’s fragile unity government has been shaken again. The country’s second-largest political party broke with partners Wednesday and voted against a national budget.

A debate on South Africa’s fiscal framework, which underpins the budget, proceeded in the National Assembly in Cape Town on Wednesday, despite objections from a number of lawmakers.