Maduro signed an order on Monday calling the citizens assembly, claiming that a new constitution was needed to stop the opposition-led National Assembly from carrying out a coup.
Maduro pointed out that the citizens assembly must be implemented immediately. He cited the articles 347, 348 and 349 of the Venezuelan constitution, which, he claimed, gave the president the authority to call such an assembly.
"We will be working with other countries in the region as well, about coordinated sanctions to the extent possible, but we also continue to look as we always do under US sanctions," Fitzpatrick said. "The actions that were taken yesterday may well give us new reasons to considering additional individual sanctions under the Venezuela Democracy Act of 2014."
Venezuela has been experiencing mass protests, triggered by an attempt in April by the country's Supreme Court to take over legislative powers of the National Assembly.
Although the top court reversed the ruling, daily demonstrations have waged for the past month.
Protesters blame Maduro for hyperinflation, food shortages and a collapsed economy, despite Venezuela’s control of some of the world’s largest proven oil reserves.