Pakistan's former military ruler Pervez Musharraf is due to face trial for treason on Wednesday, a week after the case was adjourned because of a bomb scare.
The 70-year-old stands accused over his imposition of emergency rule in November 2007, but he and his legal team have dismissed the charge as politically motivated.
Conviction could mean the death penalty or life imprisonment for Musharraf, who has faced a series of criminal cases since returning from self-imposed exile in March.
He is the first former army chief to go on trial in Pakistan, setting up a potentially destabilising clash between the government -- which brought the charges -- and the all-powerful military.
Musharraf on Sunday denounced the treason case as a "vendetta" against him and claimed he had the backing of the military.
"I would say the whole army is upset. I have led the army from the front," he told reporters at his farmhouse on the edge of Islamabad.
"I have no doubt with the feedback that I received that the whole army is... totally with me on this issue."
There has been no public comment on the case from the army, but some observers say they are reluctant to have their former chief suffer the indignity of trial in a civilian court.
The Taliban have made repeated threats to kill the man who led Pakistan into its alliance with Washington's "war on terror", and security for the hearing in Islamabad was tight.
The allegations are the latest in a series of criminal cases faced by Musharraf since he returned to Pakistan in a thwarted bid to run in May's general election.
These include murder charges over the assassination in late 2007 of former prime minister Benazir Bhutto.
The treason case was due to start on December 24 but had to be delayed after police found explosives and a detonator on Musharraf's route to court. A second scare came on Monday when more explosives were found on the same road.
It is unclear who left either set of explosives, which were not made up into bombs.
In a similar mysterious episode in April, a car with explosives stuffed into its doors and seats was found near Musharraf's farmhouse on the same day he appeared in court over the Bhutto case.
The former commando's lawyers have dismissed the charges as an attempt by the government of Prime Minister Nawaz Sharif, whom Musharraf ousted in a coup in 1999, to settle old scores through the courts.
Musharraf spokesman Raza Bokhari said they have filed challenges to the tribunal's authority and the hearing should not go ahead until rulings have been made on these.
"We demand that the unlawfully formed special treason court avoid the label of being called a 'kangaroo court" and suspend its proceedings until the challenges raised by General Musharraf are heard and properly disposed by the superior courts," Bokhari said in a statement issued late Tuesday.
They have urged the United Nations to intervene in what they call a "stage-managed show trial" and have asked London and Washington to "repay their debt" for Musharraf's support in the wake of the 9/11 attacks.