CARACAS, Venezuela -- Rival political factions took to the streets across Venezuela on Saturday in a mounting struggle for control of the crisis-wracked nation, where U.S.- backed opposition leader Juan Guaido is attempting to oust socialist President Nicolas Maduro.

It was the first march Guaido has led since Maduro loyalists stripped him of legal protections he's granted as a congressman, opening a path to prosecute and possibly arrest him for allegedly violating the constitution.

The rallies also follow crippling power failures that left most of the country scrambling in the dark for days and without running water or phone service.

Speaking before several thousand people who packed a broad Caracas avenue, Guaido urged them to stay united and to keep up pressure until Maduro leaves power.

"Something is evident today," Guaido said. "Venezuela is not afraid and continues taking the streets until we get freedom."

Guaido tried to channel Venezuelans' ire by calling crowds in the capital to march to the headquarters of the national power utility, Corpoelec. His supporters said the blackout is another failure of the socialist government.

"This regime has made big mistakes," said Beatriz Cisneros, a 62, critical of Venezuela's deteriorated petroleum industry, its broken educational system and hospitals that fail to provide basic care. "We're fighting for Venezuela to have liberty."

Many opposition supporters marched along a sunny main avenue carrying Venezuelan flags. A nun draped the national colours around her shoulders. Another protester carried a sign listing the lack of power, water and other basic services, along with the slogan: "Don't get used to it."

Meanwhile, crowds of Maduro backers, many dressed in bright red and gathered in the centre of Caracas, waved flags and danced around a stage blasting music ahead of a march to the presidential palace.

"Let's fill the streets of Caracas with joy," Maduro tweeted. "Together, in an unending mobilization, we'll defend our nation's peace and independence. No more interference!"

Guaido, 35, arose from relative obscurity in January when he was named head of Venezuela's opposition-dominated National Assembly and said he was assuming presidential powers to force Maduro from power. He says Maduro is illegitimate due to allegedly fraudulent elections last year.

He has gained support from Washington and roughly 50 nations, but he has yet to budge Maduro, who maintains control over the government and military and is backed by foreign allies including China, Cuba and Russia.

Washington on Friday added to pressure on Maduro by imposing financial sanctions on two companies involved in shipping oil from Venezuela to Cuba, along with nearly three dozen ships. Maduro blames the recent blackouts on U.S. "cyber-attacks" as part of a coup attempt to topple his government.

Guaido, meanwhile, has come under increasing pressure from Maduro's government, which recently jailed his chief of staff and has taken legal actions that could lead to his own arrest, though the administration of President Donald Trump has warned of a strong response if the opposition leader is harmed.

Amid the Maduro supporters was Ana Margarita Urbina, 57, who wore a bright red shirt, the colour of Venezuela's socialist party, saying she marched to defend the country she said is under threat from the imperialist United States.

"We're on a mission," said Urbina. "We have a common cause. Our country is our mother."

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Associated Press writer Christopher Torchia contributed to this report.