ISLAMABAD - Thousands of Pakistani riot police took up position to defend a key diplomatic and political enclave of the capital on Tuesday after an opposition leader vowed to march on parliament to oust the prime minister.
Former cricket star Imran Khan said Monday that he would lead thousands of supporters in a peaceful march, but the government had banned him from the "Red Zone", which houses many Western embassies, parliament and the office and home of Prime Minister Nawaz Sharif.
Khan said he was determined to march there and many of the young men following him appeared raring to go. Many in the crowd carried sticks or tree branches.
"My blood is boiling today and I want to be martyred," said 20-year-old Shams Khan, who came from the northwestern region of Bannu with his friends. "If we don't go into the Red Zone today, I will quit this party tomorrow."
The protests have piled extra pressure on the 15-month-old civilian government as it struggles to overcome high unemployment, daily power cuts and a Taliban insurgency.
The protests have also raised questions over the political stability of Pakistan, a nuclear-armed nation of 180 million people with a history of coups.
In addition to Khan's protest, firebrand cleric Tahir ul-Qadri has also led his supporters to the capital to bring down Sharif.
Police estimate the two men have around 55,000 supporters between them. But Qadri has not yet committed to joining Khan, saying he would consult his supporters later in the day.
Their protests have so far remained separate because the two have different supporters and plans for what should happen if Sharif steps down.
Khan says Sharif rigged last year's polls to secure his landslide win. Qadri says Sharif is corrupt. The government says Sharif will not go and law enforcement will prevent protesters from reaching the Red Zone.
"This challenge to the writ of the state will not be acceptable under any circumstances," said Marvi Memon, a legislator from Sharif's party, during a press conference.
"By entering the Red Zone, what are you trying to prove?" she asked. "You cannot just go and sit on his chair and become prime minister."
Outside the capital, police in Punjab, Pakistan's wealthiest and most populous province, arrested 147 supporters of Khan and Qadri overnight to prevent them joining the protests in Islamabad, said Inspector Rana Hussain in the central town of Sargodha.
Khan also announced his party, the third largest in the country, would resign from their 34 seats in the National Assembly and in all provinces apart from Khyber Pakhtunkhwa, which his party controls.
Khyber Pakhtunkhwa, which borders Afghanistan, is the heartland of the Taliban insurgency. If Khan's legislators resign, Pakistan will have to hold a raft of by-elections.
Memon said no formal resignations had been received so far.
Police have estimated the number of people at the protests at around 55,000, including many women and children. Khan has called for his supporters to bring their families on the march.
Pakistan's newspapers have criticised Khan, with many running editorials accusing him of seeking to provoke a violent confrontation after failing to muster the numbers needed to oust Sharif.
So far, the country's powerful military has remained silent on the protests. Some analysts believe Khan and Qadri mounted their challenge because Sharif's relationship with the military had deteriorated in recent months, appearing to leave the fledgling civilian government isolated.
However, Sharif, a conservative businessman who ran promising to fix the economy and power crisis, has a large power base. He won a landslide victory in last year's election, taking a majority of seats in parliament.
Sharif also has some support from the judiciary, which warned last week that the protesters should not consider any "unconstitutional" action.