LA PAZ, Bolivia — In her first televised address to the nation Wednesday, the senator who assumed Bolivia’s interim presidency, Jeanine Añez Chavez, urged a return to normalcy after weeks of violence, even as the ousted president, Evo Morales, called her government unconstitutional and his backers vowed to disrupt it.
With the backing of the military, Ms. Añez met with advisers on Wednesday to appoint a new cabinet. In a speech, she rejected charges that her assumption of the presidency after Mr. Morales’s resignation was illegitimate, and emphasized that she said wanted to seek “a national consensus” and “to reconstruct democracy.”
But outside, in the streets of La Paz, a chaotic scenario played out, leaving clear that Bolivia remained deeply polarized and volatile four days after Mr. Morales resigned amid widespread unrest.
On Wednesday afternoon, after using tear gas to break up a peaceful protest by supporters of Mr. Morales, the police blocked about a dozen senators affiliated with the former president from entering the legislature, as the crowd accompanying the lawmakers chanted, “dictatorship, dictatorship.”
Less than an hour later, as tear gas wafted outside the government palace, the armed forces announced a shake-up of the high command. Army General Carlos Orellana Centellas became the new top commander of the armed forces and promised to take orders from the newly installed Ms. Añez, who had the backing of the Constitutional Court.
“We will guarantee the security of the constitutional government,” said General Orellana Centellas.
Mario Galindo, a noted Bolivian political science professor, said the political situation was confusing and in flux.
“At this moment, it is not clear who is in charge of whom,” he said. Under Bolivian law, the senators “had all the right to enter the senate and meet with whomever they wanted.”
Supporters of Mr. Morales, Bolivia’s first Indigenous president, remained skeptical of Ms. Añez, accusing her and the opposition of staging a coup.
“We want Morales to return,” said Graciela Argollo, a Quechua radio station translator from Cochabamba, one of the marchers. “Añez must resign. She’s not with the farmers and poor people.”
Ms. Añez declared herself the head of Bolivia’s caretaker government before a special session of the legislature on Tuesday night. She had been next in the line of succession after Mr. Morales resigned on Sunday, followed by a series of high-ranking officials, and has said she intends to stay in power only until new elections can be held, in 90 days.
But the session at which she seized the presidency was boycotted by supporters of Mr. Morales, who possess a majority.
In Mexico City, where Mr. Morales has sought asylum, he told reporters that Ms. Añez’s government was unconstitutional because the legislature had not approved his resignation.
He said he would return to Bolivia “if the people ask me to return to pacify” it, but he also said he was willing to bow out if it would unite the country and end the violence.
“Without Evo if they want, but without violence, because that isn’t the solution,” he said. “But it doesn’t depend just on Evo.”
Mr. Morales also defended his record of lifting Bolivia’s long-repressed Indigenous communities out of poverty, reeling off economic statistics to prove his success — down to the miles of roads that had been paved under his presidency.
“Continuity is important for the economic development of the country,” he said.
The political crisis and subsequent demonstrations were set off by the recent disputed presidential election in which Mr. Morales, 60, declared victory.
His grip on power swiftly began to erode as the opposition said the vote had been rigged and protesters poured into the streets. The Organization of American States, which had monitored the elections, said that the Oct. 20 vote had been marred by irregularities and that the group could not validate Mr. Morales’s victory.
Some police units defected and joined the protests, and military officials called on Mr. Morales to resign.
A former media executive and conservative legislator, Ms. Añez quickly gained the support of the Bolivian Army’s high command, who visited her on Wednesday for a planning meeting at the government palace. Her backers released photos of members of the high command saluting her.
Looting and clashes between the police and demonstrators across the country have left at least eight dead in recent weeks, according to Bolivian news reports.
The new government was welcomed enthusiastically by crowds in Santa Cruz, a longtime center of dissent against Mr. Morales, and other localities. But it appears that few people know much about Ms. Añez, who took power from an obscure legislative post.
“I can’t say that I like her or not,” Victor Pusari, the son of an apartment building porter, who was guarding the entrance of his central La Paz building, said on Wednesday. “But we need a leader, someone to be in charge.”
On Wednesday, police officers guarding the assembly said they expected crowds of Morales supporters to descend for a third day in a row from El Alto, a nearby mountain city with a heavy Indigenous population. This time, they were expected to be joined by pro-Morales lawmakers who might try to retake the assembly.
Some Bolivians said they were prepared.
“When they come, we’re here to defend,” said Jarameel Armas, a university student who joined the police at a barricade of corrugated metal and heavy chains. “We will defend the new government and the democracy we have won.”