Bolivia faces its worst unrest in decades amid a political vacuum as Evo Morales, who transformed the Andean nation as its first indigenous president, fled the country after weeks of violent protests.

He landed in Mexico on a Mexican government plane late on Monday hours after being granted asylum, as his supporters and opponents fought on the streets of the Bolivian capital while an opposition leader tearfully laid out a possible path towards new elections after his resignation.

Mr Morales stepped down on Sunday after weeks of widespread protests fed by allegations of electoral fraud in the October 20 presidential election that he claimed to have won.

Resignations by every other constitutionally designated successor left unclear who would take his place and how.

Clashes in La Paz
Clashes in La Paz (Juan Karita/AP)

His flight from the country was a dramatic fall for the llama shepherd from the Bolivian highlands and former coca growers’ union leader who as president helped lift millions out poverty, increased social rights and presided over nearly 14 years of stability and economic growth in South America’s poorest country.

In the end his downfall was marked by his insistence on holding onto power.

“It pains me to leave the country for political reasons, but I’ll always be concerned,” he said on Twitter. “l’ll return soon, with more strength and energy.”

Mexican foreign minister Marcelo Ebrard published a photo of him holding the flag of Mexico, saying the plane had left Bolivia and that Mr Morales was safe.

Evo Morales
(Evo Morales/Twitter/AP)

In an earlier tweet, Mr Morales posted a photo of his first night after he resigned showing him lying on a floor with an improvised blanket as a bed. He said had been forced into these conditions after what he has called a coup by the opposition.

Angry supporters of the socialist leader set barricades on fire to close some roads leading to the country’s main airport on Monday, while his foes blocked most of the streets leading to the capital’s main square in front of Congress and the presidential palace.

Police urged residents of La Paz to stay in their homes and authorities said the army would join in policing efforts to avoid an escalation of violence.

The Senate’s second vice president, opposition politician Jeanine Anez, said in an emotional address that she would take temporary control of the Senate, though it was unclear if she would get approval from Congress, which is controlled by Morales supporters.

She would become next in line for the presidency if chosen to head the Senate.

Jeanine Anez
Jeanine Anez (Natacha Pisarenko/AP)

“Please excuse me if my voice breaks,” she said between tears after arriving in Congress under heavy guard. “It’s so hard to see Bolivians clashing, no matter which side they’re on. They are being mistreated, and I’m asking you to cease the violence.”

Ms Anez said she would convene a legislative session on Tuesday to consider accepting the formal resignation of Mr Morales. It was unclear if legislators could meet that soon because of insecurity in the capital.

As tensions grew, local media reported that Morales supporters were marching on La Paz from the nearby city of El Alto, a Morales stronghold, to try to break the street blockades thrown up by his opponents and to reach the capital’s main square.

General Williams Kaliman, the chief of the armed forces, announced the joint police-military operation in a television address. He said the hope was to “avoid bloodshed and mourning of the Bolivian family”, and he urged Bolivians to help restore peace.

Police guard Congress in La Paz
Police guard Congress in La Paz (Natacha Pisarenko/AP)

Anti-Morales demonstrators in central La Paz set tyres and other barricades on fire as other people went on to their rooftops to yell “Evo, murderer!”

Rock-throwing demonstrators also clashed in Cochabamba and other cities.

His presidency, the longest among serving leaders in the region and the longest ever in Bolivia, ended abruptly on Sunday, hours after Mr Morales had accepted calls for a new election by an Organisation of American States team.

The team reported a “heap of observed irregularities” in the election whose official results showed Mr Morales getting just enough votes to avoid a runoff that analysts said he could lose against a united opposition.

Mr Morales stepped aside only after the military chief called on him to quit, saying that was needed to restore peace and stability.

His vice president also resigned as did the Senate president. The only other official listed by the constitution as a presidential successor, the head of the lower house, had resigned earlier.