The Treasury Department slapped sanctions on Nicolas Maduro on Monday, alleging that Venezuela's president has attempted to undermine democracy and the rule of law in his country.

On Sunday, Venezuela held a controversial election to create the National Constituent Assembly (ANC), a constitutional assembly that would grant Maduro's party sweeping power. But many countries said they would not recognize that vote.

Treasury Secretary Steven Mnuchin said those who participate in the illegitimate assembly could face "future U.S. sanctions for their role in undermining democratic processes and institutions in Venezuela."

The ANC, which many expect to be stacked with Maduro supporters, would be able to rewrite the country's constitution.

In a statement, Mnuchin continued: "Yesterday's illegitimate elections confirm that Maduro is a dictator who disregards the will of the Venezuelan people. By sanctioning Maduro, the United States makes clear our opposition to the policies of his regime and our support for the people of Venezuela who seek to return their country to a full and prosperous democracy."

Venezuela has been engulfed in an economic crisis, featuring skyrocketing inflation and food shortages. The country's economy had been tied to its oil exports but was sent into a downward spiral amid crashing oil prices in 2014.

In recent months, protesters have flooded the streets of Venezuela as clashes have turned violent, with more than 100 people killed in the chaos.

What's happening in Venezuela is "the end of the constitution," national security advisor H.R. McMaster told reporters later Monday. He said that the erosion of democracy in the country has been accelerating.

"By designating Maduro himself, he joins a very exclusive club, including Mr. [Robert] Mugabe, Bashar al-Assad and Kim Jong Un," McMaster said during the daily White House press briefing.