(CNN) A day after Venezuela's embattled president and his opposition rival held dueling rallies in the capital Caracas, opposition leader Juan Guaido said he will call for a "state of national emergency" in a special session of parliament on Monday.

The South American nation continues to struggle with an ongoing power outage -- parts of Venezuela remained without power over the weekend after 70% of the country had an outage late last week, and officials warned that hospitals were at risk.

Guaido, Venezuela's self-declared interim president, said Sunday that 16 states continued to be completely without power, while six have partial power. He said the private sector has lost at least US $400 million from power outages.

Meanwhile, embattled President Nicolas Maduro blamed the United States for the blackout, telling supporters at a rally Saturday that the nation's electric grid had been sabotaged. The United States has attributed the outage to the Maduro regime's "incompetence."

At a press conference Sunday, Guaido said talks have been held with Germany, Japan, Brazil and Colombia to seek their support. Guaido said there is $1.5 billion available from multilateral organizations to take care of services in Venezuela. He did not say where the money was or how the funds could be accessed.

Guaido again appealed to the military to "stop hiding the dictator," referring to Maduro.

Rival rallies

Maduro and Guaido held separate and contentious rallies in Caracas on Saturday, with Maduro insisting that the country's power grid had been "hacked" and "sabotaged."

Maduro told supporters that almost 70% of power had been restored in the country Friday afternoon, but that progress was put off track by an "international cyberattack" carried out by the "US government" and Venezuela's opposition.

Guaido, at his rally, defiantly assured followers that all options were on the table to get Maduro out of office.

Using a megaphone and standing atop a bridge -- after police dismantled the stage he was supposed to use -- Guaido said constitutional options to promote regime change would only work if the opposition continued to protest regularly and called on citizens to travel to Caracas to protest.

Guaido also said that Article 187 of the Venezuelan Constitution is under consideration and will be activated "at the appropriate moment." Article 187 states that the National Assembly has the power to authorize the use of Venezuela military missions abroad or to allow foreign missions in the country.

He asked his supporters to remain strong in the face of the power outage.

"We have been reporting the electrical crisis for years, and now, we have to alert in a responsible manner that this could also become the gasoline crisis, in addition to the water crisis we already have."

Guaido addresses supporters through a megaphone.

Venezuela has 'already collapsed,' Guaido says

As Venezuelans continue to struggle with the nationwide power failure, Guaido said the people who died during the blackouts had been "murdered" by the government.

"Venezuela has truly collapsed already," Guaido told CNN in an interview in a sweltering hotel room in the Venezuelan capital, another byproduct of the blackouts. "There is no service in the hospitals. These were the best hospitals in the country. ... You can say with all responsibility that Venezuela has already collapsed."

Guaido said the Maduro government's accusations of a US cyberattack were absurd. Venezuela's main power plant is full of aging, analog machinery not connected to any network, he said.

"We are in the middle of a catastrophe that is not the result of a hurricane, that is not the result of a tsunami," Guaido said. "It's the product of the inefficiency, the incapability, the corruption of a regime that doesn't care about the lives of Venezuelans."

A dark corridor at Miguel Perez Carreno hospital, in Caracas, during the outage Thursday.

Maduro warns against encouraging US intervention

Maduro on Saturday announced changes inside Corpoelec, Venezuela's national electric company. The first step, he said, was to "clean" the company to get rid of "traitors" and "infiltrators."

Maduro waves a Venezuelan flag at the rally at the Miraflores Presidential Palace in Caracas.

Maduro also criticized opposition calls for a military intervention in Venezuela saying that if the US decided to carry military actions in the country, both pro-opposition and pro-government groups will be affected.

On Thursday, US Secretary of State Mike Pompeo had rejected Maduro's finger-pointing, blaming him for the situation.

"The power outage and the devastation hurting ordinary Venezuelans is not because of the USA. It's not because of Colombia. It's not Ecuador or Brazil, Europe or anywhere else. Power shortages and starvation are the result of the Maduro regime's incompetence," Pompeo tweeted.

Pompeo posted a photo of Guaido's rally with the caption: "The people of #Venezuela have again responded to @jguaido's call to take to the streets in support of freedom and democracy. Public-sector workers, suffering economic & political repression, now stand with Guaido and the promise of a better future for Venezuela."

Massive power outage continues

Rampant inflation and food scarcity have gripped Venezuela under Maduro, and thousands have fled to neighboring countries as shortages, political turmoil and crime rates have soared.

Blackouts have become a daily occurrence as the economic crisis has worsened, but one of the magnitude of the ongoing outage -- which has paralyzed most of the country -- is rare.

From Caracas, CNN's Patrick Oppmann reported that electricity returned in some areas of the city on Friday but by Saturday afternoon the entire city was without power.

"From the 26th floor of a building in Caracas there was nothing visible but a sea of blackness on Saturday. Except for a few pinpricks of light from the lucky few with generators, Venezuela's capital and home to five million people remained in the dark," Oppmann said.

"Every so often the occasional gunshot would ring out in the night. There was a run on gas and food and water and a growing sense that the Venezuelan government is unable to restore power to its citizens," he said.