LA PAZ: Former Bolivian President Evo Morales said Monday he was headed for Mexico after being granted asylum there, as his supporters and foes clashed on the streets of the capital following his resignation and a tearful opposition leader laid out a possible path toward new elections.

Morales stepped down Sunday following weeks of massive protests over a disputed presidential election, but the resignations of every constitutionally designated successor left unclear who will take his place and how.

Angry supporters of the socialist leader set barricades ablaze to block some roads leading to the country's main airport, 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 said they were joining with the army to avoid an escalation of the violence.

Morales tweeted that he was leaving Monday evening, and Mexico's Foreign Relations Secretary Marcelo Ebrard confirmed in a tweet that Morales was on a plane sent by Mexico City.

"I am leaving for Mexico, grateful for the openness of these brothers who offered us asylum to protect our life," Morales tweeted. "It hurts me to leave the country, for political reasons, but I will always be concerned. I will return soon, with more strength and energy."

Amid the power vacuum, opposition politician and Senate second vice president Jeanine Añez said in an emotional address that she would take temporary control of the Senate, though it was unclear if she would be able to get approval from Congress, which is controlled by Morales supporters.

"Please excuse me if my voice breaks," Añez 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," said Añez, who would be next in line for the nation's presidency given the leadership void.

She also said she would convene a legislative session on Tuesday to consider accepting the formal resignation of Morales, and that new presidential elections could soon follow. It was unclear, however, if lawmakers could meet that soon because of the continuing insecurity in the capital.

As tensions grew, local media reported that Morales supporters were marching down from the nearby city of El Alto, a Morales stronghold, to try to break the street blockades thrown up by his opponents and reach the main square of La Paz. Worried about a possible escalation in the violence, the armed forces agreed to work alongside police.

The joint operation would "avoid bloodshed and mourning of the Bolivian family," the head of Bolivia's armed forces, General Williams Kaliman, said in a televised address. He also called on Bolivians to help restore peace.

Police Chief Yuri Calderon said the joint mission would begin Monday and would "end when the peace is recovered."

TV showed images of Humvees and other military vehicles patrolling the streets of El Alto. In Santa Cruz, a bastion of the opposition, people welcomed the military jeeps by clapping and cheering them on.

But in downtown La Paz, anti-Morales demonstrators bracing for clashes set tires and other barricades ablaze as people went onto their rooftops to yell, "Evo murderer!" Rock-throwing demonstrators also clashed in Cochabamba and other cities.

Earlier, Morales had lashed out at his political opponents, calling his removal a return to the bleak era of coups d'etat overseen by Latin American militaries that long dominated the region. "(Opponents) lie and try to blame us for the chaos and violence that they provoked," Morales tweeted Monday.

His nearly 14-year presidency abruptly ended Sunday, hours after he had accepted calls for a new election by an Organization of American States team that found a "heap of observed irregularities" in the October 20 election whose official result showed Morales getting just enough votes to avoid a runoff against a united opposition.

Morales stepped aside only after the military chief, General Williams Kaliman, called on him to quit to allow the restoration of peace and stability. His vice president also resigned as did the Senate president, who was next in line. The only other official listed by the constitution as a successor, the head of the lower house, had resigned earlier.

Bolivian opposition leader Carlos Mesa said Morales was brought down by a popular uprising, not the military, countering Morales' claim he was the victim of a coup. The military made a decision not to deploy in the streets because "they didn't want to take lives," said Mesa who finished second in the contested October vote.

There were no immediate signs that the military itself was manoeuvring for power, although analysts warned the power vacuum opened up space for the military to potentially step in.

"I think we have to keep a close eye on what the military does," said Jennifer Cyr, associate professor of political science and Latin American studies at the University of Arizona. "Are they overstepping their role?"

Michael Shifter, head of the Washington-based think tank Inter-American Dialogue, warned that, "Bolivia is bitterly polarized and needs new leadership that is able to bring the country together."

"The temptation for any vengeance against Morales supporters needs to be resisted. That would be a recipe for continued conflict and chaos that could well put at risk some of the country's undeniable socio-economic gains over the past decade."

The first member of Bolivia's indigenous population to become president, Morales brought unusual stability and economic progress, helping to cut poverty and inequality in the impoverished nation. He remains deeply popular among many Bolivians, and his backers have clashed with opposition demonstrators in the disturbances that followed the October vote.

The leadership crisis escalated in the hours leading up to Morales' resignation. Two government ministers in charge of mines and hydrocarbons, the Chamber of Deputies president and three other pro-government legislators announced their resignations. Some said opposition supporters had threatened their families.

In addition, the head of Bolivia's Supreme Electoral Tribunal, Maria Eugenia Choque, stepped down after the release of the OAS findings. The attorney general's office said it would investigate the tribunal's judges for possible fraud, and police later said Choque had been detained, along with 37 other officials on suspicion of electoral crimes.

Morales was elected in 2006 and went on to preside over a commodities-fed economic boom in South America's poorest country. The combative former leader of a coca growers union paved roads, sent Bolivia's first satellite into space and curbed inflation.

But even many backers eventually grew wary of his reluctance to leave power.

He ran for a fourth term after refusing to abide by the results of a referendum that upheld term limits for the president — restrictions thrown out by a top court critics claimed was stacked in his favour.

After the October 20 vote, Morales declared himself the outright winner even before official results indicated he obtained just enough support to avoid a runoff with opposition leader Mesa, a former president. A 24-hour lapse in releasing results also fueled suspicions of vote-rigging.