LOTS OF PRESSURE, LITTLE SUPPORT
Some segments of the media have intensified calls for Musharraf to resign, and a lawyers movement that sprang up last year in defence of the judiciary plans a mass protest on June 10, the same day the government is due to present its budget.
Independent analyst Nasim Zehra saw few options left for Musharraf.
"I think he has no cards left," she said. "General Musharraf may be compelled to think of resigning sooner rather than later."
A general election on February 18 swept away Musharraf's parliamentary support and resulted in an uneasy alliance between Zardari and Sharif.
To add to Musharraf's sense of isolation, retired generals, including some who served under him, have publicly criticised him and called for him to go.
Under Kayani the army has adopted a more constitutional role, though it won't want its former chief humiliated.
The United States has told the new government it wouldn't want to see Musharraf dragged through the courts, as he has been a staunch ally and survived several al Qaeda-inspired assassination attempts.
Beyond that, Washington has given assurances it will not play any role in Pakistan's internal affairs, the adviser to the PPP leadership said.
Saudi Arabia's King Abdullah has asked Sharif to let Musharraf leave peacefully without pressing too hard for him to be put on trial, according to Pakistani officials.
Last November, the Saudi monarch pressured Musharraf into letting Sharif return from exile in the Saudi city of Jeddah.
Before leaving for London on Tuesday, Sharif again called for Musharraf to be put on trial for treason or impeached.
The country has been dogged by political instability since March 2007, when Musharraf galvanised a moribund opposition by starting a fight with the judiciary that resulted in him purging the judges when he imposed emergency rule.
Sharif pulled his ministers out of the PPP-led government last month after Zardari delayed reinstating the judges.
