President Nicolas Maduro danced at a pro-government rally and mocked the US as Vice-President Mike Pence prepared to meet opposition leader Juan Guaido.
A high-stakes bid by the Venezuelan opposition to transport aid into the country turned deadly as government forces opened fire on a group of volunteers.
The Trump administration and the Venezuelan opposition have staked their plans to weaken President Nicolás Maduro on a climactic moment only days away.
A delegation representing opposition leader Juan Guaido met with Vatican officials as the Holy See weighs a request to intervene in the country's crisis.
The political crisis in Venezuela shows that Latin America has again become an arena in which rival powers struggle for influence and advantage.
The world is now watching whether Maduro's government will let the first shipments from United States cross its borders.
President Nicolos Maduro has vowed to defy a growing call for him to step down in favour of Opposition Leader Juan Guaido.
The US is boosting pressure on socialist leader Nicolas Maduro to step down,but Venezuela's ally Russia is warning against"destructive meddling".
Opposition leaders hope large protests - with international sanctions - will push Nicolas Maduro to negotiate his exit or prod the military to force him out.
International Committee of the Red Cross has warned the US about the risks of delivering humanitarian aid to Venezuela without the approval of Maduro's forces.
People gathered on the streets of Venezuela's capital on Wednesday,waving their nation's flag and demanding Nicolas Maduro step down from power.