l CARACAS

Nicolas Maduro so far has led by imitation, seeking to fill the shoes of a president whose uncanny vigour, mischievous humour and political wiles sowed a revolution and transformed a nation.

As Hugo Chavez did during his 14-year presidency, Maduro has stoked confrontation, and shed tears.

While steering Venezuela through the trauma of Chavez's death, Maduro has pinned his move to the top on his beloved predecessor.

Yet there are doubts, even among die-hard Chavistas, about his ability to lead the nation.

At his swearing-in Friday evening as acting president, Maduro pledged his "most absolute loyalty" to Chavez.

Then he launched into another fiery, lionisation-of-the-masses speech punctuated by tears, Chavez-style harangues and attacks on capitalist elites and the international press.

"This sash belongs to Hugo Chavez," he said, choked up, after assembly speaker Diosdado Cabello slid the presidential band over his head. Hours earlier at Chavez's state funeral before more than 30 foreign leaders, Maduro delivered a speech similarly strident in content and tone.

Maduro, 50, hasn't stopped idolising the outsized leader who made him Venezuela's foreign minister, then vice president and, before going to Cuba for a final cancer surgery in December, publicly selected him presidential successor.

While Maduro has filled the leadership void since Chavez disappeared from public view after his surgery, many Venezuelans find him bland and uninspiring. Some blame his lack of education, noting the former bus driver never went to college.

Others say it goes much further. After all, Brazil's hugely popular former president, Luiz Inacio Lula da Silva, also started out as a worker and union leader with limited education.

"Nicolas Maduro does not embody Chavismo. He's not in touch with the people," said Carlos Borola, a 57-year-old member of a "colectivo," a radical pro-Chavez citizen's group.

"You can try to imitate the aggressivity of speech. You can try to imitate the conjuring of imaginary enemies. But you can't imitate Chavez's charisma," said Luis Vicente Leon, president of the respected Datanalisis polling firm.

"Chavez was a showman. Maduro is not," he said.

Many worry that Maduro may not be capable of managing the economic challenges of rising public debt, inflation above 20 per cent, endemic crime responsible for the world's second-highest murder rate and nagging food shortages.

As Chavez's political heir, he had three months to establish himself as the face of Chavismo. It fell to him to announce Chavez's death, and he sweated through the hours-long walk Wednesday as the funeral cortege crawled through adoring crowds, some shouting "with Chavez and Maduro, the people are secure."

When Maduro was sworn in, boisterous lawmakers shouted "Chavez lives, Maduro carries on." The ceremony was mostly boycotted by the opposition, which called it illegitimate because Venezuela's constitution says the assembly speaker should be interim president. For the socialist Chavista movement, Maduro's leftist credentials, at least, are unassailable.

He joined the now-defunct Socialist League at a young age, got some revolutionary schooling in Cuba and later, as Chavez's foreign minister, became close to Fidel and Raul Castro.

Chavez named him vice president after defeating opposition leader Henrique Capriles in the October 7 election.

Once Chavez fell from sight as his health failed after the December 11 surgery, Maduro began wielding the huge state media machine built by his mentor, mindful that Chavez was unlikely to live much longer and that a snap presidential election was likely.

He began to crisscross the nation and show up on state TV presiding over the distribution of apartments and buses for university students.

As Chavez's death drew nearer, Maduro's rhetoric grew more incendiary, while criminal investigations of opposition leaders for alleged financial irregularities were opened. He launched blistering personal attacks against Capriles, accusing him of "conspiring against the homeland" with far-right US putschists and fugitive bankers.

Maduro expelled two US military attaches for allegedly trying to destabilise the nation, just hours before he announced Chavez's death Tuesday, surprising analysts who had thought a rapprochement between the two nations might be possible under the new leader.

On Friday night, Maduro's voice boomed as he said "the imperialist elites who govern the United States will need to learn to coexist with absolute respect with the insurrectionary peoples" of South America. "Nothing and no one will take away the reconquered independence with our Comandante Hugo Chavez at its front." He did not mention how he might confront Venezuela's multiple ills, including crumbling infrastructure and diminishing production of oil, which accounts for more than 95 per cent of its exports.

Capriles, meanwhile, fired back at Maduro, saying he had withheld criticism since Chavez's death out of respect but could no longer hold his tongue at what he considered a power grab by the new leader.

One observer thinks Maduro will win the presidency if the election comes soon, but says his shortcomings will become more evident in a few months of grappling with a possible recession, another expected currency devaluation following a 30 per cent cut in February, and public impatience with deteriorating public health care and services and rising crime.

For now, Maduro can benefit from having Chavez's embalmed body on public display and the late president's son-in-law, Science and Technology Minister Jorge Arreaza as his running mate, reminding Venezuelans of who chose him to lead the nation.

But people like Edgar Carvajal, a 50-year-old employee of the Chinese appliance company Haier, said people could lose patience.

"We've got to trust in Maduro, but he had better take care of all these shortages we're having and the high prices," Carvajal said Friday while standing in the long line of people waiting to view Chavez's body lying in state.

"If Maduro can't handle it, the people will show him the door," Carvajal said.

* Frank Bajak of the Associated Press

co-wrote this article.