ISLAMABAD, Pakistan — The Pakistani government has mounted a counterattack against moves by the country's military and Supreme Court that could result in what critics call a constitutional coup against President Asif Ali Zardari.

The Supreme Court had set a Jan. 10 deadline for the government to request that a Swiss court reopen a corruption case against Zardari, but his ruling Pakistan People's Party said Thursday that the government would ignore it. At a meeting held at the presidential offices — in defiance of a court order against such use of the premises — the party said it would uphold the president's constitutional immunity from prosecution.

The party also said that Zardari wouldn't respond to a summons from a judicial inquiry ordered by the Supreme Court to investigate allegations that a top Zardari aide had sought White House help to dissuade the Pakistani military from staging a fifth coup in 64 years.

The moves figured to prolong a standoff that has brought Pakistani politics to a standstill and threatens to imperil U.S. efforts to enlist Islamabad's help in achieving peace in neighboring Afghanistan. With military officials seemingly bent on removing Zardari — whom they view as a threat to their considerable power — and the president digging in his heels, the turmoil also has distracted attention from the country's worsening economic difficulties and a decisive phase of its war against Pakistani Taliban insurgents.

Four major Pakistani Taliban factions had on Sunday pledged to end attacks on Pakistani security forces and join the war against U.S.-led NATO forces in Afghanistan. However, the pledge rang hollow on Thursday after one faction, led by Hakimullah Mahsud, announced it had executed 15 paramilitary soldiers kidnapped from a fort in December.

The Supreme Court panel's inquiry focuses on a memo that Pakistan's former ambassador to Washington, Hussain Haqqani, is alleged to have drafted for Gen. James Jones, who was then President Barack Obama's national security advisor. The claim was made in October by an American businessman of Pakistan origin, Mansoor Ijaz, who said he delivered the memo.

Jones has acknowledged receiving the memo and forwarding it to the then-chairman of the Joint Chiefs of Staff, Adm. Mike Mullen. Both have said they doubted Ijaz's claims and hadn't considered the memo to be authentic.

The Pakistani government has rejected Ijaz's claims. It was furious when the army chief and the head of the military spy agency, the Inter-Services Intelligence directorate, told the Supreme Court in December that they believed Ijaz's claims warranted a judicial investigation.

The ensuing rhetorical back-and-forth in court and in the Pakistani media have sparked rumors of a coup against Zardari.

His government appeared to win a boost Wednesday when opposition leader Nawaz Sharif — who had filed the petition asking the Supreme Court to look into Ijaz's claims — said that he'd welcome negotiations with the government on efforts to rein in the military. Sharif has feuded with the military since it overthrew him as prime minister in 1999, forcing him into a 10-year exile in Saudi Arabia.

"I don't think the government is really serious about restricting the political role of the army and intelligence services, but if it is, I'm ready for talks," he told Geo, the leading Pakistani cable news channel.