The Catalan regional parliament was preparing on Monday to strip the president of the troubled region of his seat after he disobeyed Spain's strict rules on election propaganda.
Quim Torra was found guilty of disobedience after refusing to remove, from public buildings, the yellow ribbons used by separatists to call for the release of imprisoned politicians and activists.
The secessionist symbols had been displayed during Spain's general election in April, which violated the country's strict rules on campaigning.
Spain's electoral board ruled that Torra should be stripped of his seat after a Catalan court barred him last month from public office for 18 months for disobedience.
He has appealed, but Spain's Supreme Court last week ruled that the electoral board's decision should be enforced immediately while judges make a decision.
Parliamentary officials announced the decision to strip him of his seat earlier Monday, but it has to be formally confirmed by the house.
The expected move is likely to fuel anger among hard-core pro-independence supporters, who see in the decision by the governing body of Catalonia's parliament yet another grievance with Spanish judicial decisions.
Torra, a hardcore separatist, will be allowed to remain as the head of Catalonia's regional government but he has threatened to call a new regional election.
Separatist supporters were expected to protest later Monday in front of the Catalan regional parliament.
The secessionist movement in the Catalonia region of 7.5 million is Spain’s most significant political challenge in decades.
Polls show residents in Catalonia are roughly evenly divided over the question of independence from Spain.
Spain’s constitution rules that the country is indivisible.