CARACAS, Venezuela — Opposition leader Juan Guaidó stepped up efforts Tuesday to remove President Nicolás Maduro, meeting with public-sector unions and calling for rolling strikes in a bid to weaken the authoritarian government.

Guaidó managed to draw about 100 leaders of state- employee unions to the session. But only a few hundred workers came, with many citing fears of government retaliation. It was a dramatic sign of the challenge that Guaidó faces in dislodging a radical leftist government that has resisted both international pressure and street demonstrations.

The meeting came a day after Guaidó arrived in Venezuela to a raucous welcome, after a 10-day trip abroad. Many Venezuelans had feared he would be arrested upon return, effectively shutting down an anti-government movement that had gathered steam since January, winning support from the White House and dozens of countries. 

Instead, the authorities allowed him back in. But Maduro still controls the state apparatus, including the powerful military

Juan Andrés Mejía, an opposition lawmaker, said Guaidó’s strategy was to “isolate the regime.” That involved reaching out not just to the military but to other parts of Maduro’s base, Mejía said. Public-sector unions “have been part of the regime’s strategy to stay in power,” he said, with employees pressured to attend pro-government marches.

Guaidó announced that unions would hold meetings with their members starting Wednesday to plan when and how to launch work stoppages. “The pressure is just beginning,” he said. “Every union is now going to fight for its rights.” Guaidó also promised a new law to prevent the abuse of public-sector workers. 

One union leader at the meeting, Besse Mouzo, said the plan involved organizing work stoppages that would eventually lead to a general strike. “We have to begin by convincing people” to join the smaller strikes, she said.  

Venezuela’s government is believed to be the country’s biggest employer, with an estimated 2 million employees. As Guaidó met with union leaders, a few hundred government workers arrived to show their backing for the opposition leader.  

One worker, from the federal public notary and registry office, said the majority of the department’s 4,000 employees supported Guaidó.

“There aren’t many here,” he acknowledged, speaking on the condition of anonymity. “We’re all afraid that we’ll be fired” if we demonstrate loyalty to the opposition, he said.

Lenin Briceno, 54, a retired central bank employee, said at least 80 percent of his former colleagues backed Guaidó. He sent invitations to hundreds of them to attend the event on Tuesday, he said.

“The answer was that I should take care. That they hoped I’d succeed. I didn’t receive answers about whether people would come. They’re too afraid,” Briceno said. “Now that I’ve arrived, I don’t see any of them.” 

A Foreign Ministry professional wept as she stood with others at the outdoor pavilion in downtown Caracas. “I’m indignant that we aren’t allowed to protest,” she said. “We have nothing to lose. We no longer have medical insurance. We aren’t well paid. Your paycheck isn’t even enough to buy chicken and cheese.”

“It’s risky for me to be here,” she continued, speaking on the condition of anonymity because she fears losing her job. “But I am hoping for change.”   

Maduro has become deeply unpopular as Venezuela’s economy has disintegrated, with hyperinflation topping 1 million percent and supplies of food and medicine dwindling. 

Guaidó declared himself interim president several weeks ago, maintaining that Maduro’s reelection to a second term starting in January was invalid because of widespread irregularities in the vote last year. Guaidó, who had been serving as leader of the National Assembly, has since been recognized as president by more than 50 countries, including the United States. On Feb. 22, he crossed the border into neighboring Colombia, violating a court-imposed travel ban, to attend a concert hosted by billionaire Richard Branson to raise money for humanitarian aid for Venezuela. The following day he led thousands of Venezuelans in an attempt to transport internationally donated food and medicine into Venezuela, an effort that was almost entirely blocked by Maduro, who called it a veiled attempt to invade the country.

Maduro had suggested that Guaidó might be detained upon his return on a charge of violating the travel ban. Maduro has not made any public comment on the opposition leader’s return. Instead, he posted a video Tuesday on Twitter commemorating the anniversary of the 2013 death of Hugo Chávez, Maduro’s predecessor and mentor, who led what he called a socialist revolution in this oil-rich nation.  

Maduro has accused Guaidó of attempting to pull off a coup, with U.S. support. 

“Guaidó has a very complicated task ahead of him,” said Félix Seijas, an analyst and statistician who teaches at the Central University of Venezuela. “While people’s hopes have soared with his arrival, there are few things he can do to put pressure on the government.” 

The opposition “needs to transmit to people that they are advancing, with firm steps,” ­Seijas said. “If not, people could get discouraged.”

Mariana Zuñiga contributed to this report.