Most Western countries, including the United States, have recognised Guaido as Venezuela's legitimate head of state, but Maduro retains the backing of Russian Federation and China as well as control of state institutions including the military.
But Maduro, whose government has the financial and political backing of China and Russian Federation, has so far resisted the intensifying USA pressure, portraying himself in the mold of historic Latin American anti-imperialist leaders.
The administration is investigating how to get tens of millions of dollars worth of aid from the United States into Venezuela that Guaidó promised would be delivered starting February 23.
"With respect to the new sanctions on PDVSA, I appreciate the need to squeeze Maduro", Engel said.
Venezuela is already facing severe shortages of food and medicine. "You have people starving in Venezuela".
The Wall Street Journal said the diplomats, concerned about oil projects in Venezuela and nearly US$20 billion that Caracas owes Beijing, had held talks in Washington with representatives of Juan Guaido, the opposition leader heading US-backed efforts to oust President Nicolas Maduro.
President Donald Trump is headed to Miami on Monday to speak about the ongoing turmoil in Venezuela, a move that could embolden interim president Juan Guaidó and put further pressure on Nicolás Maduro to flee the country. "We have nearly 300,000 Venezuelans who will die if the aid doesn't enter".
Maduro, who gets crucial backing from the country's powerful armed forces, denies there is a humanitarian emergency and has branded the crisis a "political show" and pretext for a US-led invasion.
Guaido's team has also met with Brazilian officials to set up a second aid storage center on that border. The new right-wing government of President Jair Bolsonaro in Brazil, which took over in January after more than a decade of leftist rule there, has joined the coalition against Maduro.
But Maduro has so far resisted, portraying himself in the mold of historic Latin American anti-imperialist leaders.
Russian Foreign Minister Sergei Lavrov warned U.S. Secretary of State Mike Pompeo on Tuesday against U.S. intervention in the internal affairs of Venezuela, including the use of force.