Islamabad, Aug 25: Pakistan is facing one of its worst political crises in the present era. An estimated 50,000 protesters, who are holding Islamabad city to ransom, marched to Parliament demanding Prime Minister Nawaz Sharif's resignation. The twin anti-government protests by cricket star-turned politician Imran Khan and activist cleric Tahir ul-Qadri are targeted at ousting the PML-N-led government on charges of corruption and inflation. Imran Khan, who is leading the 'Azadi March', is also protesting against the alleged vote rigging that took place in last year's polls. However, PM Sharif is ready offer Khan a full audit of the ballots to address his concerns on poll rigging.