Despite the tough talk from the White House, the sanctions fell short of the crippling pressure many observers were expecting. Maduro swiftly dismissed the measures, saying on television that they were imposed because he didn't obey the "North American empire". He added: "Impose all the sanctions that you want, but I'm a free president".
Potentially more-sweeping measures - including the targeting of Venezuela's all-important oil industry - are still on the table. But the opposition here is running out of time to turn the tide, and is now facing new and significant threats.
The election was boycotted by the opposition, and many Venezuelans mocked the Government's contention that more than 40 per cent of voters took part. Under Maduro's mentor, the late leftist leader Hugo Chavez, many Venezuelans thought national election results were generally credible, although candidates complained that he used state resources to gain an edge. But opposition activists called Monday's vote a turning point, claiming that only about 12 per cent of Venezuelans turned out, in what they called a historic rejection of Maduro and his plans.
Luisa Ortega Diaz, Venezuela's attorney-general, who broke with the Government in March, yesterday declared the vote fraudulent. She suggested that Maduro and his inner circle, including a vice-president accused by the US Government of narco-trafficking, would now seek to use the new assembly to monopolise money and power. "How will we control the public budget now? How will we know how much and in what things money is being invested? How amazing for them!" she said.
Maduro has said he proposed the assembly to bring peace to the streets after four months of often-violent demonstrations protesting the dire state of the economy and growing authoritarianism. Opponents said he skewed the system for choosing candidates to ensure control of the new body.
On Friday, those chosen for the new Constituent Assembly are set to replace the democratically elected members of the nation's legislature, which is dominated by the opposition. Some opposition lawmakers defiantly went to the National Assembly building yesterday, vowing to keep carrying out their duties. It foreshadowed a potentially dramatic standoff.
With more than 100 dead and thousands detained in the demonstrations, some people are tired, and even more are scared.
"Today I feel crushed," said Victoria Daboin, 25, who has been protesting since April. "I feel depressed because today everything looks normal, as if nothing had happened. The streets are empty and people went to work as if nothing ever happened. I personally expected more forceful actions from opposition leaders."
