ISLAMABAD (AP) — Pakistani lawmakers met Wednesday as tens of thousands of protesters thronged outside parliament calling for the resignation of Prime Minister Nawaz Sharif over alleged voting fraud.

Sharif and other lawmakers entered the building through a back exit connected to the heavily guarded premier's office after the protesters torn down barricades late Tuesday and entered the so-called "Red Zone" housing parliament and other key government buildings.

The twin protests led by the famous cricketer-turned-politician Imran Khan and the cleric Tahir-ul-Qadri have virtually shut down Islamabad, raising fears of unrest in the nuclear-armed U.S. ally with a history of military coups and dictatorships.

Sharif has refused to step down, while the country's powerful army has called for a negotiated settlement.

The "situation requires patience, wisdom and sagacity from all stakeholders to resolve prevailing impasse," army spokesman Gen. Asim Saleem Bajwa said on Twitter. He said the government buildings in the "Red Zone" were a "symbol of state" protected by the army.

Pakistan TV showed Sharif entering the National Assembly, the lower house of parliament, and meeting with lawmakers from all the major parties except Khan's Pakistan Tehreek-e-Insaf, the legislature's third-largest bloc.

Lawmakers from several parties condemned the protesters' attempt to besiege parliament.

"We will foil this conspiracy and we will defend our democratic institutions," said Maulana Fazlur Rehman, head of the Jamiat Ulema-e-Islam party and a Sharif ally.

Shazia Marri, a lawmaker from the opposition Pakistan People's Party, said: "We will strive to safeguard democracy. We will strive for the supremacy of the constitution."

Outside of parliament, Qadri briefly directed his supporters to occupy all the main gates of the building and not to allow Sharif or any other deputies to leave until the prime minister resigns.

"We deliberately gave these lawmakers a chance to enter the parliament, but now we will not allow any lawmaker to go inside or come out," he said.

Hours later, Qadri softened his stance after meeting with a government committee assigned by Sharif for talks with him.

Hyder Abbas Rizvi, one of the members of the committee, thanked Qadri for agreeing to the talks and he urged Sharif's government to make arrangements for providing food and water to the protesters.

Khan warned Tuesday that his supporters would enter the premier's office if Sharif did not step down by Wednesday night, but his party appeared to back down later, urging supporters not to enter government buildings and indicating it would take part in talks to resolve the crisis.

"We are ready for the talks. We will present our six demands when we hold any such talks," senior party official Shah Mahmood Qureshi told a Pakistani news channel. Khan, however, has repeatedly said he will only hold talks with the government after Sharif's resignation.

The Supreme Court, acting on a petition, summoned Khan and Qadri over the sit-ins, ordering them to appear before a judge either in person or through their attorneys, according to Pakistan TV.

The protesters accuse Sharif of rigging the May 2013 election that brought him to office in the country's first-ever democratic transfer of power.

Sharif was forced from office after a previous stint as prime minister in 1999, when the then-army chief Pervez Musharraf seized power in a coup.

A peaceful and celebratory atmosphere prevailed outside the parliament, with protesters dancing to drums, singing patriotic songs and chanting slogans against Sharif.

"Yesterday, people were saying we will never be able to reach the parliament. Look, we are standing right in front of the parliament," said Rabia Naeem, 22.

Asad Hafeez, a 45-year-old Qadri supporter, said new laws were needed before any new elections.

"We need electoral reforms and a neutral government to hold free and fair elections. It will only happen when Nawaz Sharif resigns," he said.

The U.S. Embassy in Islamabad said its consular section was closed Wednesday, and advised American citizens to keep a low profile and avoid large gatherings.