Islamabad: Pakistan’s political opposition Wednesday demanded an immediate timetable for polls, but dealt a blow to a massive anti-government protest by refusing to endorse their four-day demonstration.

At least 25,000 people are estimated to be taking place in the largest rally in the capital since the current government took office in 2008 and leader Tahir-ul Qadri on Wednesday urged mainstream politicians to support his cause.

But the leader of Pakistan’s opposition, Nawaz Sharif, announced after consultations with main opposition parties that they would not be joining Qadri in a move that appeared to isolate the populist Canadian-Pakistani cleric.

“This meeting demands from the government that an election schedule and caretaker set-up should be announced without any delay and dates for these events specified forthwith,” Sharif, who was unseated as prime minister by a military coup in 1999, announced at a news conference in Lahore.

Qadri’s protest rally has threatened to destabilise the nuclear-armed country as it inches towards what would be the first democratic transition of power between two civilian governments at elections due by May this year.

The economy is struggling, Taliban and other violence is at a high, the rupee is sinking, there is an appalling energy crisis and fledgling peace gains with India appear in jeopardy following five deadly cross-border shootings in a week.

On Tuesday, the Supreme Court ordered the arrest of the prime minister, sparking panic among some observers about a judiciary-military plot using Qadri as a frontman to disrupt the democratic process.

The government has not announced any date for polls other than saying that parliament will disband in mid-March to make way for a caretaker government and elections within 60 days under the constitution.

Qadri wants parliament dissolved now and a caretaker government set up in consultation with the military and judiciary to implement key reforms such as setting up a new election commission and banning corrupt candidates.

But Sharif defended the current election commission, saying: “People should refrain from making any demands which are not in the ambit of the constitution.”

Sharif said the Supreme Court had not acted in consort with Qadri by calling for the arrest of Prime Minister Raja Pervez Ashraf.

Ashraf later issued a statement welcoming the opposition parties’ position. Commentators say there is no imminent sign that he will be arrested and that he can remain in office until and unless he is convicted.

Qadri’s sudden — and apparently well-financed — emergence after years in Canada has been criticised as a ploy by the establishment, particularly the armed forces, to delay the elections and sow political chaos.

In a three-and-a-half hour speech delivered behind bulletproof glass, Qadri urged his followers to remain steadfast, despite the winter cold, in their demands for key reforms and clean elections.

“Keep sitting, don’t move. Be steadfast. Your destiny is closer. There will soon be a decision in your favour,” Qadri shouted to the crowd, which has brought the main commercial avenue in Islamabad to a standstill for three days.

Information minister Qamar Zaman Kaira ridiculed the cleric, accusing him of staying in a “seven-star bunker” while women and children camp out in the chilly nights and issued a veiled threat alluding to his possible arrest.

“If he will go beyond law and constitution, then certainly law will take its own course,” Kaira told reporters.

While critics dismiss Qadri’s supporters as a rent-a-crowd, many of Qadri’s supporters articulate real concerns about Pakistan’s problems, digging in for the long-haul, with supplies of food, water and mattresses and blankets.

Police clashed briefly with stone throwers and protesters on Tuesday, shooting into the air and firing tear gas. Eight officers were injured.

Rally organisers accused police of opening fire and trying to arrest Qadri.