Members of Venezuela’s opposition have sat down with the government for talks aimed at defusing the nation’s political crisis as embattled President Nicolás Maduro seeks to fend off an intensifying campaign for his removal.

The talks that extended until 2 am on Monday ended with both sides agreeing to tone down the heated rhetoric of the past few days and immediately open four thematic negotiations on topics ranging from human rights to the economy. Those talks will be mediated by a Vatican envoy and the former presidents of Spain, Panama and the Dominican Republic, all of whom were present at a museum in western Caracas to kick off the talks alongside Maduro.

Thomas Shannon, the US under-secretary of state for political affairs, was also scheduled to arrive on Monday “to underscore our support for the ongoing dialogue process”, the state department said in a statement.

The talks are mired in distrust. Many of the president’s foes fear they could be a stalling tactic designed to ease pressure on the unpopular socialist leader, whom many Venezuelans blame for triple-digit inflation and widespread food and medicine shortages.

Fifteen parties belonging to the Democratic Unity opposition alliance boycotted the talks, saying they are not prepared to sit across from the government until it releases several jailed opposition activists and reverses its decision to cancel a constitutionally allowed recall referendum against Maduro.

“For an eventual dialogue to take place it has to be very clear from the outset that the aim is agreeing on the terms of a democratic transition in the remainder of 2016,” the parties said in a statement.

The talks come as the opposition is stepping up its campaign seeking to force Maduro from office.

Last week it rallied tens of thousands of supporters across the country, and another protest has been called for Thursday at which the opposition is vowing to march to the presidential palace. Government foes have not been allowed to get close to the palace since the 2002 coup that briefly toppled President Hugo Chávez, the late leader who installed the socialist administration.

The opposition-controlled congress, meanwhile, has begun a “political trial” against Maduro accusing him of neglecting his duties, though it is a largely symbolic gesture since the body doesn’t have the power to remove a president under Venezuela’s constitution.

Although he has threatened to arrest legislators if they go ahead with the trial, Maduro said on Sunday night that he has an “absolute commitment” to holding a dialogue with the opposition.

“We’re giving a chance to disarm the hatred, the intolerance, and open the door to love among the Venezuelans,” he said in televised remarks from the museum.

Previous attempts have been made at having a dialogue between the opposition and the government, such as talks that followed a wave of deadly unrest in 2014. Those sessions calmed the streets but failed to produce any meaningful progress on key issues dividing Venezuelans.

Archbishop Claudio Maria Celli, a Vatican envoy to the talks, hailed the start of the latest round of talks as something “very positive”. He urged both sides to make concessions in order for the talks not to falter like the previous attempts.

“At the start of this journey, I ask you in the name of Pope Francis that each side agrees to some concrete gestures to give credibility to this process,” said Celli, who is president of the pope’s council for social communications. “The country is waiting for authentic signals to comprehend that dialogue is a reality.”

Jesús Torrealba, who attended the meeting as head of the Democratic Unity alliance, said the opposition’s patience is limited.

“Without freedom for the political prisoners in the next few days this process of dialogue can’t continue,” he told reporters after emerging from the meeting.