OREANDA-NEWS.  Venezuelan president Nicolas Maduro is facing a snowballing domestic campaign to unseat him and mounting regional scrutiny as the oil-based economy skids.

Leaders of Venezuela?s political opposition said today they have collected more than 1.5mn signatures on a petition to conduct a referendum to revoke Maduro?s presidency, far exceeding a minimum threshold needed for a vote.

A defiant Maduro has pledged to remain in office, and has repeatedly challenged the national assembly since the opposition took control there in January, mainly using allies on the supreme court to block or dismiss legislative action and hearings.

The power struggle coincides with a growing throng of street protests, sparked by acute shortages of food, medicine, water and electricity.

The plunge in oil prices since mid-2014 has evaporated government revenue, undermining vast social programs and impeding repairs to crippled infrastructure, including oil refineries, terminals and power stations.

Venezuela?s high-profile efforts to rally the world?s main oil producers around a price-stabilizing proposal to freeze production at a 17 April meeting in Doha failed, leaving Caracas in a deep economic morass.

In a victory for the opposition that regularly lobbies for international support, Organization of American States secretary general Lu?s Almagro is studying the invocation of Article 20 of the 2001 Inter-American Democratic Charter, which would allow the body to take unspecified steps toward restoring democracy.

"In the event of an unconstitutional alteration of the constitutional regime that seriously impairs the democratic order in a member state, any member state or the Secretary General may request the immediate convocation of the Permanent Council to undertake a collective assessment of the situation and to take such decisions as it deems appropriate," the article states. The council "may undertake the necessary diplomatic initiatives, including good offices, to foster the restoration of democracy."

The article is ambiguous with respect to specific actions.

Caracas has traditionally enjoyed political backing from most of its neighbors, particularly small Caribbean and Central American countries that still rely on the Opec country for subsidized oil supply. But regional support has eroded in recent years, after Venezuela?s state-owned oil company PdV started withdrawing from regional downstream projects and Venezuelan oil supplies became less reliable.

Caracas lost a critical regional ally in Argentina after president Cristina Fernandez de Kirchner completed her term in December 2015. Her successor, Mauricio Macri, is a market advocate and a staunch opponent of Venezuela?s radical brand of socialism.

Another Venezuelan ally in South America, Brazilian president Dilma Rousseff, is close to impeachment.

The International Monetary Fund forecasts that the Venezuelan economy will contract by 8pc in 2016, with 720pc inflation.