Guaido, the National Assembly speaker, has so far been recognized by around 40 countries since declaring himself interim president on January 23.

But Maduro maintains the support of the armed forces and important allies Russia and China, which have massive investments in a country with the world's largest oil reserves.

Here are four scenarios that according to several Latin America experts could tip the balance either way as Venezuela struggles with the worst economic crisis in its recent history.

-Negotiation-

Maduro has called for "face to face" talks with Guaido and to that end is supporting the Contact Group meeting, starting Thursday, of European and Latin American countries in Montevideo. However, Guaido has rejected any negotiations, seeing it as a way for Maduro to buy time.

Negotiation remains unlikely unless the army distances itself from Maduro and "puts in place another interlocutor," says Anna Ayuso, of the Center for International Affairs (CIDOB) in Barcelona.

At Maduro's request, Pope Francis said he would be willing to mediate but only if both parties were willing.

The socialist president "could accept negotiations in exchange for the lifting of sanctions and relaxing of international pressure," according to Ernesto Pascual, political scientist at the Open University of Catalonia.

Four previous attempts at dialogue between the government and the opposition have failed since Maduro came to power in 2013.

-Invasion-

The United States gave immediate recognition to Guaido and has not ruled out military intervention, though Washington has until now opted to squeeze the economic life out of Maduro's administration, according to analyst Luis Vicente Leon.

Several experts said the catalyst could be some kind of armed action to block US humanitarian aid shipments.

Maduro has rejected humanitarian assistance, seeing it as a precursor to a US military incursion. Venezuelan soldiers late Tuesday moved tanker trucks and shipping containers to block a crossing point on the border with Colombia.

"But I don't think it interests the United States to get involved in a conflict, any more so than Colombia and Brazil," said Ayuso.

Any military intervention would require consensus, unlikely to be forthcoming, according to Pascual, given the precedents of Iraq and Afghanistan.

Leon believes Maduro will try to avoid the use of force to impede aid deliveries. A complicating factor is that any kind of military intervention would possibly unleash a wave of violence by pro-government militias.

"The risk exists," says Leon.

- Implosion-

For analysts, the military holds the key to the crisis. And despite the appearance of cracks in the edifice of military loyalty to Maduro, the high command is still with the socialist leader.

For any "internal collapse" or implosion to happen, "it would be necessary for the military and the Chavistas to distance themselves. This would be the end of the revolution," Leon said, referring to the leftist ideology and government style of late president Hugo Chavez.

Pascual says it's "unthinkable" the armed forces would abandon Maduro "because of the high command's vested interests in oil and mining."

Guaido has offered them an amnesty deal. But a month on, there are no signs he has won them over.

"An implosion occurs when the actors understand that they have guarantees of protection," said Leon. He suggested Guaido's offer was still too vague.

"The military sector needs face-to-face negotiations" with specific officials, "an international guarantor and probably a pardon being enshrined in the constitution," he said.

- Isolation -

Maduro could entrench himself and close ranks "Cuban style", says Ayuso, with "very painful consequences" for a population devastated by shortages and hyperinflation.

"It's a terrible scenario because it does not solve the problem and makes the situation in the country worse," said Leon.

Ayuso believes that such a move would also open the way for even "greater repression" of the opposition and "a more harsh military government."