President Nicolas Maduro has accused foreign countries of trying to mount a coup and is calling for rival demonstrations. There are fears of clashes.
In what could be an escalation of recent political conflict in Venezuela, the opposition has called the first in a series of mass protests against the government on Wednesday.
It comes amid an economic crisis which began under the rule of former President Hugo Chavez, but has escalated sharply under President Nicolas Maduro.
But President Nicolas Maduro refuses to hold a referendum that could force him to step down.
Now he's accusing foreign powers of pressuring the opposition to overthrow him.
"The time for combat has arrived my fellow patriots. People alert. The hour has arrived to decide the future and the destiny of our country; and we are in the crucial hours of the destiny of our country," Maduro said in a statement. "I will be in front at this battle."
TRT World's Sarah Jones has more.
TRT World spoke to Juan Carlos Lamas who has the latest on the protests against Maduro's government in the Venezuelan capital Caracas.