Venezuelan opposition leader Juan Guaido, who has declared himself interim president, greets supporters at a rally  in Valencia, Venezuela, Saturday, March 16, 2019. Large crowds gathered in the northern Venezuelan city to greet Guaido, who plans to tour the country as part of his campaign to oust President Nicolas Maduro. (AP Photo/Fernando Llano)

VALENCIA, Venezuela (AP) — Venezuelan opposition leader Juan Guaido embarked on a new stage of his campaign to oust President Nicolas Maduro on Saturday as the rivals held competing rallies in the capital of Caracas, a pattern which has unfolded repeatedly as both sides attempt to convey strength.

Addressing large crowds in the northern city of Valencia, Guaido pledged to deliver a better life for struggling Venezuelans as he began a planned tour of the country gripped by an economic and political crisis.

"We're stronger than ever," said U.S.-backed Guaido from a podium draped with a large Venezuelan flag.

The leader of the opposition-controlled National Assembly also drew cheers with his denunciations of Maduro, although he warned that difficult challenges still lie ahead.

Earlier in the day, he visited a cathedral and a market in Valencia, where people flocked to take his picture and shake his hand.

Since returning to Venezuela from a Latin American tour on March 4, Guaido has led anti-government activities in the capital of Caracas and announced plans to take his message to other regions. But he has been unable to force Maduro to step down and hold elections.

On Saturday, the government organized its own flag-waving demonstration in Caracas, attracting large numbers of people to the street. Many were clad in red, the color associated with the movement led by the late President Hugo Chavez, the former military officer who declared a socialist "revolution" after coming to power in 1999. He was succeeded after his 2013 death by his protege, Maduro.

Diosdado Cabello, a leading pro-government politician, evoked the defiant rhetoric of Chavez, denouncing the U.S. and declaring: "We won't surrender."

In Washington, other demonstrators rallied in front of the White House to protest what they call U.S. interference. "Hands off Venezuela!" they chanted.

Maduro has remained in power despite heavy pressure from the United States and other countries arrayed against him, managing to retain the loyalty of most of Venezuela's military leaders.

The latest demonstrations come as the South American country recovers power in many areas after widespread blackouts inflicted misery on millions of people, cutting off running water and communications.

Guaido and the U.S. said corruption and mismanagement by the government caused the outages, while Maduro claimed that the U.S. had launched a "cyberattack" on the national grid in an ongoing attempt to oust him. Maduro has routinely described Guaido as a collaborator in a U.S. coup plot.

Coinciding with the demonstration in Valencia, opposition lawmakers organized smaller anti-government gatherings in the northwest city of Maracaibo, where many areas were devastated by looting during the blackouts.

Meanwhile, U.S. Sen. Tim Kaine traveled to the Colombian side of the border with Venezuela, which was the scene of a Feb. 23 attempt by Guaido to deliver U.S.-provided aid.

Maduro said the aid mission was actually an attempt to undermine his government's authority and security forces blocked it from entering Venezuela, escalating tensions with the U.S. and dozens of other countries that support Guaido.

During his visit, Kaine visited a soup kitchen and tweeted that the U.S. will continue to try to provide humanitarian assistance.

Guaido declared himself interim president in January, saying Maduro's re-election last year was illegitimate because major opposition figures were not allowed to run.

Venezuela's opposition leader and self-proclaimed interim president Juan Guaido, sings the national anthem at the end of a rally in Valencia, Venezuela, Saturday, March 16, 2019. (AP Photo/Fernando Llano)
Supporters hold their hands up promising to help Venezuelan opposition leader Juan Guaido, who has declared himself interim president, at a rally in Valencia, Venezuela, Saturday, March 16, 2019. (AP Photo/Fernando Llano)
A supporter of Venezuela's opposition leader and self-proclaimed interim president Juan Guaido holds a flyer depicting him, as she waits for his arrival during a rally in Valencia, Venezuela, Saturday, March 16, 2019. (AP Photo/Natacha Pisarenko)
Supporters cheer for Venezuelan opposition leader Juan Guaido, who has declared himself interim president, amid a sculpture depicting the Statue of Liberty, at a rally in Valencia, Venezuela, Saturday, March 16, 2019. Large crowds gathered in the northern Venezuelan city to greet Guaido, who plans to tour the country as part of his campaign to oust President Nicolas Maduro.  (AP Photo/Natacha Pisarenko)
Supporters of Venezuela's self-proclaimed interim president Juan Guaido wave to him as he leaves after attending a rally in Valencia, Venezuela, Saturday, March 16, 2019. (AP Photo/Natacha Pisarenko)
Supporters of Venezuelan opposition leader Juan Guaido, who has declared himself interim president, arrive to attend a rally in Valencia, Venezuela, Saturday, March 16, 2019. (AP Photo/Natacha Pisarenko)
Activists gather to oppose the
Activists yell to oppose the,
Supporters of Venezuela's President Nicolas Maduro holds a national flag as they take part in an anti-imperialist march in Caracas, Venezuela, Saturday, March 16, 2019.  Many were clad in red, the color associated with the movement led by Chavez, the former military officer who declared a socialist
Supporters of Venezuela's President Nicolas Maduro cheer an anti-imperialist march in Caracas, Venezuela, Saturday, March 16, 2019. Many were clad in red, the color associated with the movement led by Chavez, the former military officer who declared a socialist
Supporters of Venezuela's President Nicolas Maduro take part in an anti-imperialist march in Caracas, Venezuela, Saturday, March 16, 2019. Many were clad in red, the color associated with the movement led by Chavez, the former military officer who declared a socialist
A supporter of President Nicolas Maduro holds a painting depicting the late president Hugo Chavez on the right corner, and President Nicolas Maduro during an anti-imperialist march in Caracas, Venezuela, Saturday, March 16, 2019.  Many were clad in red, the color associated with the movement led by Chavez, the former military officer who declared a socialist