A furious Maduro responded to the US move by breaking off diplomatic ties with the 'imperialist' US government
Venezuelan leader Nicolas Maduro prepared to rally his military supporters Thursday as the US and key allies backed a challenge from his leading rival who declared himself "acting president."
The announcement by Juan Guaido, 35, head of Venezuela's opposition-led legislature, came amid a fresh wave of deadly street clashes on Wednesday.
He declared himself acting leader of the oil-rich nation, which has lurched into economic chaos and violence under Maduro, 56.
The Socialist government responded by warning that the top military leadership would come out Thursday "in support of the constitutional president", Defence Minister Vladimir Padrino Lopez said.
He added the military would show "backing for the sovereignty" of Venezuela.
That was a warning shot to Maduro's foreign critics as they rallied behind Guaido.
US President Donald Trump declared Maduro "illegitimate" and called the National Assembly legislature "the only legitimate branch of government."
A furious Maduro responded to the US move by breaking off diplomatic ties with the "imperialist" US government, giving its diplomats 72 hours to leave.
The US State Department said it did not recognize Maduro as president anymore so his order meant nothing.
France added its support for Guaido, also branding Maduro "illegitimate" and calling for "the restoration of democracy" in Venezuela.
Maduro's key ally Russia meanwhile denounced Guaido's bid as a "usurpation" of power and condemned what it called foreign "interference" in Venezuela.
"This is a direct path to lawlessness and bloodshed," the Russian foreign ministry said in a statement.
Maduro's key financial backer China also weighed. Foreign ministry spokeswoman Hua Chunying said China opposes "interference" in Venezuelan affairs and called for a "political resolution."
Military support key
Maduro was reelected in May in snap elections boycotted by the opposition and denounced around the world as illegitimate.
He has held onto power in the face of mass protests, international pressure and opposition efforts to oust him.
Analysts at the Eurasia Group consultancy said his opponents could only prevail if the top military command abandon him.
They said Trump might consider further economic sanctions against Venezuela, from which the United States buys more than a million barrels of oil a day.
Guaido called on the military to join "the side of the constitution" and offered an amnesty to any Maduro allies who would defect.
He was elected president of the National Assembly - the only major state pillar not controlled by the government - in December.
Since then, he has managed to rally a divided opposition.
"I have faith and hope in Guaido, a young lad who can help us to go forward," one demonstrator in Caracas, 49-year-old Florangel Rodriguez told AFP.