Venezuelan opposition leader Juan Guaidó has called for an escalating series of strikes to force President Nicolás Maduro to relinquish power.
Mr Guaidó urged public employees to act on Thursday, saying the stoppages would lead to a general strike.
A woman was killed in clashes between protesters and security forces in Caracas on Wednesday, reports say.
Mr Maduro meanwhile dismissed suggestions he had been ready to flee and accused the US of directing a coup.
Those involved would be punished, he said.
Tensions over the crisis are also rising between the US and Russia.
US Secretary of State Mike Pompeo said the US could take military action to resolve the crisis and accused Russia and Cuba of destabilising the country through their support for Mr Maduro.
Russian Foreign Minister Sergei Lavrov told Mr Pompeo that America's influence over Venezuela was destructive and a violation of international law.
Mr Guaidó declared himself Venezuela's interim leader in January and has been recognised by more than 50 countries, including the US, the UK and most in Latin America.
But Mr Maduro - backed by Russia, China and the top of the country's military - has refused to cede power.
In a series of tweets (in Spanish), Mr Guaidó said the final phase of the "Operation Liberty" had begun and it was the turn of public workers to join in.
He urged protesters to stay on the streets until Mr Maduro's government would be finally forced to resign.
Mr Guaidó has been courting the public sector for weeks - but winning their support will be difficult, the BBC's Americas editor Candace Piette says.
For years, state employees have been told that if they did not turn up at government rallies they would lose their jobs.
So if the opposition leader does win them over, it will be a huge victory against President Maduro.
On Wednesday both pro- and anti-government supporters held large demonstrations.
Both were initially peaceful but there were then reports of gunfire in the city. Later on Wednesday a local NGO, the Venezuelan Observatory of Social Conflict, said a 27-year-old woman had been shot dead during a rally in the opposition stronghold of Altamira.
At least 27 people were injured in the clashes.