About two months ago, Venezuelan President Nicolás Maduro did something drastic: He announced that Venezuela needed a new constitution. He would create a "constituent assembly" to draft the document, elections for which will be held Sunday.

It was a dramatic move, one that only deepens the country's crisis. Opposition activists had already taken to the streets to protest Venezuela's eroding democracy and decaying economy, and after Maduro's announcement, they redoubled their efforts. Even some of Maduro's closest allies told him he'd gone too far.

But he has refused to back down.

So on Sunday, without benefit of a referendum indicating that a majority of the country wants its 1999 constitution rewritten, Venezuelans will go to polls to select members for the new assembly. The group of 545 is likely to be packed with Maduro loyalists, experts say. 

It's a scary moment for the country's democracy, once considered a South American success story. It's also complicated. Here are some key things to keep in mind:

What, exactly, is Maduro proposing?

Maduro wants to call to order an assembly that will rewrite the constitution. Technically, he has the power to do this — it's what President Hugo Chávez did when he rewrote the constitution in 1999. There's a key difference though: Chávez kicked off the process with a national referendum on whether the constitution needed a reboot. Once he won that vote, he held a second election for the assembly. Maduro wants to do something similar, but he's skipped the first step. On Sunday, Venezuelans will have only one choice: who should represent them in the assembly.

Another key difference: Chávez's constituent assembly was dissolved after it finished its work. It's not clear that that will happen this time around.

How will the new assembly work?

There will be 545 delegates to the assembly. About two-thirds (364) will be chosen according to geography. Each of the country's municipalities will get to select one delegate; state capitals get two; Caracas gets seven. Because Venezuela is a predominantly urban country, and because the more populated states have fewer municipalities, this will give rural voters (who support Maduro) significantly more say in the assembly's makeup. To take one example: The state of Miranda, population 3 million, will get four fewer delegates than Falcon, home to about a third as many people.

What will the constitution say?

When Maduro announced the vote, he claimed that the new constitution would bring peace to Venezuela. In a speech, he said he aimed to "let the sovereign people impose peace, harmony and true national dialogue." "Votes or bullets, what do the people want?" Maduro asked a crowd at the announcement.

Few specifics have been discussed. It's not clear what will be changed or rewritten. The fear, though, is that allies of Maduro will use the opportunity to target opposition leaders, silence dissent and install an ever-more-autocratic regime with fewer (or no) checks and balances.

First lady Cilia Flores hinted that the assembly will create peace and justice commissions to ensure those responsible for the current political upheaval "pay and learn their lesson." This suggests that Maduro might crack down severely on those who oppose him.

Diosdado Cabello, first vice president of Venezuela’s socialist party, says the assembly will strip legislators in the opposition-controlled National Assembly (the country's current legislative body) of their immunity from prosecution. If that happens, it could provide Maduro with another tool to go after lawmakers who oppose him. Cabello also said that it will "turn upside down" the office of Venezuela’s chief prosecutor, which is currently run by an outspoken Maduro critic.

Why are people saying that this poses an existential threat to Venezuelan democracy?

The National Electoral Commission (led by Maduro loyalists) has given the constituent assembly "total power to change any existing constitution and create a new legal order. The ‘constituent assembly’ also has the power to dissolve the National Assembly and change current legislation." If the assembly gets rid of the National Assembly, Maduro and his allies will control all branches of government.

Maduro has taken other steps to consolidate power. Last year, he quashed a legal initiative for an election to recall him. He packed the Supreme Court with loyalists; then it tried to dissolve the National Assembly. Since March, more than 100 protesters have died at the hands of pro-government forces, and more than 3,000 people have been arrested.

The constituent assembly, though, represents a major escalation. As the New York Times put it: "the new assembly will rule above all other governmental powers — technically even the president — with the kind of unchecked authority not seen since the juntas that haunted Latin American countries in decades past. 'This is an existential threat to Venezuelan democracy,' said David Smilde, an analyst at the Washington Office on Latin America, a human rights advocacy group."

How has the opposition responded? 

Ever since Maduro's Supreme Court tried to strip the National Assembly of its power, the opposition has been hosting near-daily mass protests and general strikes.

And while the main opposition parties are boycotting Sunday's vote, which they call unconstitutional, they held their own nonbinding referendum a couple of weeks ago. That referendum asked voters whether they wanted a new constitution. Nearly half of all eligible voters,  or 7.2 million people, came out to cast their ballots against Maduro's National Assembly plan. They showed up even though there were threats of violence. One voter lost her life. Overwhelmingly, these voters oppose the constitutional rewrite.

What do ordinary Venezuelans think?

The constituent assembly remains highly unpopular in Venezuela. One poll found that just 23 percent of the country support the idea; only 19 percent say a new constitution would "guarantee the peace of stability of the country." Half of those polled say the real purpose is to keep Maduro in power.

Even so, millions of people will probably show up to vote Sunday. In part, that's because the government has access to data showing who does and doesn't come to the polls. State and government workers worry that if they don't come, they'll be penalized. And with triple-digit inflation and horrifying food shortages, no one can afford to lose their job. As one person told CNBC: “They’re obliging us to vote . . . If not, they’ll fire us.” HIV patients say officials have threatened to cut off their access to their medicine if they don't vote.

Luis Vicente Leon, president of the Venezuelan polling firm Datanalisis, said he believes people will vote because they have to. "If this was a free election, without pressure, about a third of the number that participated in the popular consult would vote," he told the Associated Press, referring to the opposition referendum.

If this is so unpopular, why is Maduro doing it? After all, he's already the president.

When Maduro was elected president in 2013, he had a tough task in front of him. He inherited a country with unsustainable government spending and an economy completely reliant on the price of oil. As oil prices dropped, Venezuela suffered.

Four years later, life in Venezuela is nearly impossible. The country has one of the highest inflation rates in the world. Though it sits on massive oil reserves, people cannot buy basic things such as food and medicine. (Roughly 80 percent of medicines are unavailable, and people are so hungry that three-quarters of the country lost about 20 pounds last year.) Violent crime is rampant.

Today, Maduro's approval rating is in the low 20s. Opposition protests are massive. There's discord in the ruling party, and people are beginning to get impatient with the leader. I'm no Maduro whisperer, but the constituent assembly seems like a gamble to enable him to hold onto power by a leader who knows he can't hang on using the avenues currently available to him.

What will happen next?

It's impossible to predict, but there are a couple of things we can expect.

International groups have spoken out strongly against Maduro. And the United States, a key trading partner, has warned that if Maduro goes forward with this vote, it will impose heavy sanctions. We don't know exactly what those will look like. But if they're severe enough, they could deal a death blow to the country's economy, as the United States buys nearly half of Venezuela's oil.

The opposition will probably continue to rally support on the streets. The opposition-controlled National Assembly may try to consolidate its power by appointing its own judges. That's got experts worried about the possibility of parallel governments.

And the constituent assembly itself is a wild card. It will have so much power that it could do anything. It could even remove Maduro from office. “It’s a crapshoot, a Pandora’s box,” Alejandro Velasco, a Venezuelan historian at New York University who studies the country’s leftist movements, told the New York Times. “You do this, and you have so little control over how it plays out.”

One thing is for sure: The fight between Maduro and his enemies won't end anytime soon. Protests and widespread political activism will probably continue at least until the next presidential election. That's slated for next year. But with a new constitution in the works, who knows when it will be held, if ever?