Maduro vowed to fight his enemies in the spirit of former president Hugo Chavez, and accused the USA of stoking the unrest through the sanctions.
With the exception of Mexico, the Lima Group - made up of 14 mostly Latin American countries - has urged Maduro to renounce his second term and deliver power to parliament.
"Even as Jamaica took this vote, we were also represented by our embassy in Caracas at the swearing-in ceremony of President Maduro as a sign of our interest in remaining engaged with Venezuela, with which we maintain diplomatic relations". He denies being a dictator and often accuses President Donald Trump of leading an economic war against Venezuela that is destroying the country.
"The United States remains steadfast in its support of the Venezuelan people and will continue to use the full weight of US economic and diplomatic power to press for the restoration of Venezuelan democracy", Pompeo said.
Last May, Maduro declared victory following an election that his political opponents and many foreign nations consider illegitimate because popular opponents were banned from running and the largest anti-government parties boycotted the race (See related story on Pages 6 & 7). Output has plummeted to less than a third of that. Critics blame years of rampant corruption and mismanagement of the state-run oil firm PDVSA.
Maduro also took the opportunity to complain how Latin America, once celebrated by leftists around the world as a hotbed of socialism, had been "contaminated" by the election of right-wing leaders, including Brazil's Jair Bolsonaro, who he labeled a "fascist".
An estimated 2.3 million Venezuelans have fled, according to the United Nations.
Venezuela's splintered opposition movement has failed to counter the socialist party's dominance as Maduro's government has jailed or driven into exile its most popular leaders.
"We call on the armed forces, the majority of men and women in uniform who refuse to be corrupted, to step forward", said Congress chief Juan Guaido at a news conference.
The Trump administration has increased pressure on Maduro through financial sanctions, this week singling out powerful Venezuelan media magnate Raul Gorrin. USA banks are also banned from doing business with Venezuela, putting a financial strangle-hold on the cash-strapped country.
David Smilde, Tulane University expert on Venezuela, said that this isn't likely to create change. The opposition says the government's control of foreign exchange, in place since 2003, has generated $300 billion in illicit gains. "He has the money".
The political opposition is severely constrained as Maduro continues to enjoy the support of the military.
"It's not the president's fault", said Frances Velazquez, a 43-year-old mother of two who survives on government-subsidized boxes of rice, flour and cooking oil. Velazquez blamed opportunists who drive up the prices of scarce items for making life hard for families like hers.
Others, like construction worker Ramon Bermudez, have lost hope of escaping Maduro's rule and planned on hunkering down at home for the inauguration.