Asif Ali Zardari leads the race to replace Musharraf in Saturday's presidential election.
Nawaz Sharif and Asif Ali Zardari – the two leaders of the ruling coalition that split Monday – will battle for influence in next week's presidential election.
More than 300,000 people have fled their homes as fighting worsens between security forces and militants.
The unpopular leader announced Monday he would step down, avoiding the drive to impeach him.
Pakistan's unpopular president resigned Monday, leaving a divided government to pick a successor and face other mounting problems.
Government strategy has been ineffective, and officials are preoccupied with bid to oust Musharraf.
The ruling coalition has vowed to move forward with an impeachment process against the president. Even some of the unpopular leader's allies are urging him to quit.
The case against Aafia Siddiqui, who has been missing since 2003, raises questions about illegal detention centers across Pakistan.
Rising prices and a falling stock market have sparked protests in recent weeks, increasing the pressure on a government already facing militancy, political discord.