The second-largest party in Pakistan’s ruling coalition held firm Saturday against providing President Pervez Musharraf legal guarantees against prosecution, a stance that could prove a hurdle in efforts to avoid his impeachment.

Allies and rivals of Musharraf have said backchannel talks are under way that could lead to the president’s exit before an impeachment motion reaches parliament. Ruling coalition officials said Saturday that a draft of the impeachment charge sheet is awaiting final approval from senior party leaders and that proceedings could begin early next week.

Musharraf spokesman Rashid Qureshi insisted Friday that the president is not stepping down.

Whether he changes his mind could depend on if Musharraf’s rivals can stomach granting him immunity and the freedom to stay in Pakistan in exchange for his resignation.

On this issue, divisions have appeared in the ruling coalition.

Sadiqul Farooq, a spokesman for the party of ex-Prime Minister Nawaz Sharif - who Musharraf ousted in his 1999 coup - said legal guarantees were out of the question. His party has said Musharraf should be tried for treason, which carries a maximum punishment of death.

“It will be in the interest of the country and the nation to make him an example in accordance with the constitution and the law,” Farooq said.

That’s a tougher tone than the line taken by the senior coalition member, the Pakistan People’s Party headed by Asif Ali Zardari, the widower and political successor of slain ex-Prime Minister Benazir Bhutto.

Asked Friday if Musharraf could get legal assurances, senior party member and Defense Minister Ahmad Mukhtar replied: “If a person moves to the side, we are not in the habit of bothering him. This would not be a good attitude, if someone is lying on the ground and we go aggressively against him.”

Musharraf dominated Pakistan for years after seizing power in the bloodless military coup, gaining favor from the U.S. after supporting it in the war on terrorism. He gave up his dual role as army chief late last year, but by then he had grown very unpopular.

Many Pakistanis blamed rising violence in their country on his alliance with the United States against the Taliban and al-Qaida. His popularity hit new lows in 2007 when he ousted dozens of judges and imposed emergency rule in bids to avoid challenges to his rule.

The United States has toed a publicly neutral line since the coalition declared its impeachment plans last week, as has Pakistan’s army, Musharraf’s former power base. If he chooses not to quit, Musharraf could be the first president in Pakistan’s turbulent history to be impeached.