Venezuela’s Supreme Court has asked for opposition leader Juan Guaidó to be stripped of his parliamentary immunity, a move that could lead to his jailing.
The pro-government Constituent Assembly is expected to back the request.
Mr Guaidó declared himself interim leader in January, gaining the support of more than 50 countries including the US.
But President Nicolás Maduro has major allies too and retains the crucial backing of the military.
Amid a power struggle between the two, Venezuela has seen growing street protests over a lack of water and electricity.
The authorities have said they will shorten the working day and keep schools closed due to power cuts.
On Monday, the Electricity Minister, Luis Motta, was replaced with an electrical engineer.
The government has claimed the blackouts are the result of sabotage to force Mr Maduro from office.
What did the court say?
The court ruling said Mr Guaidó should be prosecuted for violating a travel ban when he toured several Latin American countries a few weeks ago.
The Supreme Court has already banned him from holding office for a period of 15 years and arrested his right-hand man on terrorism charges.
Mr Guaidó has not recognised the decision as having any legitimacy and is unlikely to change anything in his attempt to remove and replace Mr Maduro as president, the BBC’s Will Grant in Caracas says.
But our correspondent adds it raises the pressure and brings Mr Guaidó closer to being arrested.
The US have repeatedly warned the Maduro government that arresting or harming Mr Guaidó would have “serious consequences”.
What’s the background?
Mr Maduro narrowly won a presidential election in 2013 after the death of his mentor, President Hugo Chávez. He was elected to a second term in 2018 in an election seen as flawed by international observers.
Venezuela has experienced economic collapse – inflation was 800,000% last year. Three million people have left.
Mr Guaidó has accused President Maduro of being unfit for office, and won the support of many in the country as well as US and EU leaders.
The Maduro government is becoming increasingly isolated but Russia has expanded co-operation with Caracas – increasing arms sales and extending credit.