Despite a flurry of efforts to broker a truce, Pakistan's government and leading opposition politicians continue to stagger toward a head-on collision. As Washington and its allies watch with mounting anxiety, the government has broadened its crackdown, requisitioning troops and silencing a leading TV news channel. A senior government minister has resigned in protest over the media clampdown, but President Asif Ali Zardari appears unwilling to negotiate under pressure. And his chief rival, former Prime Minister Nawaz Sharif, is pressing ahead with preparations for a lawyer-led protest march due to arrive in the capital of Islamabad on Monday. Set against a backdrop of growing Islamist militancy and economic insecurity, fears are growing that the current clash between political rivals could push the country further toward the precipice. Senior U.S. and British envoys have attempted to pull the two sides back. In the most high-profile intervention yet, Secretary of State Hillary Clinton made phone calls to both Zardari and Sharif on Saturday. According to a statement from the Pakistani President's office, Clinton "discussed the prevailing situation in Pakistan and said the U.S. was keen to see a stable and democratic system strengthened in the country." Earlier in the week, the U.S. ambassador to Pakistan paid visits to Zardari and Sharif, while the Obama Administration's special representative to the region, Richard Holbrooke, held a videoconference with Zardari and later telephoned the opposition leader as well. British Foreign Secretary David Miliband and the United Nations Secretary General Ban Ki-Moon have issued similar appeals. (See photos of the attacks on the Sri Lankan cricketers) As the Obama Administration prepares to dispatch 17,000 extra troops to neighboring Afghanistan, its principal aim is to keep Islamabad's attention on stanching the flow of militants across the border. Toward that end, Army Chief Gen. Ashfaq Kayani who has been keen to win support for his troops' faltering campaign against the militants met on Friday with Zardari and his Prime Minister, Yousaf Raza Gilani. Although Pakistan's army has routinely staged political interventions, analysts believe that it is unwilling to seize power in another military coup. But as Zardari and Sharif joust for control over Punjab, the largest province and the home of the bulk of the army, it could yet assert its clout through backstage maneuvers. For the moment, however, troops have been asked to secure Islamabad and other "sensitive areas" in the event of violent clashes. "When the situation deteriorates, gets out of hand of police, paramilitary [troops], only then the army is deployed," Maj. Gen. Athar Abbas, the military's chief spokesman, told the Associated Press. The government says that a gathering of tens of thousands of protesters outside its main official buildings could paralyze the government or spark riots that could derail the fragile political system. There are also claims of terrorist threats. The protesting lawyers, who have called for a prolonged sit-in in the capital until their demands are met, insist theirs is a peaceful movement that has faced violence but never backed it. They have accused the government of cracking down on dissent in a manner reminiscent of former President General Pervez Musharraf's own actions when he imposed a state of emergency in November 2007. In recent days, more than 1,000 lawyers and activists have been arrested as roads have been blocked in a desperate effort to halt the march. Section 144, a British colonial-era law that forbids any gathering of four or more people, has been extended to the North West Frontier Province although armed militants seem exempt from the order. In the central city of Multan, police and intelligence officials impounded vehicles, forcing the protesters to make the journey on foot. Under a beaming sun, they were overcome by exhaustion, just a few miles out of the city. Travel bans have been imposed on three leaders of the lawyers' protest. The comparisons with Musharraf's authoritarian tactics sharpened when, on Friday evening, two of Pakistan's lively TV news channels went off the air across vast swath of the country. Aaj TV's broadcasts were limited by cable operators, as Geo News, the most popular news channel, disappeared altogether in major cities. The channel's management accused Zardari of directly ordering the shutdown charges that the President's spokesmen strenuously deny. "At around 7 p.m., we began receiving reports that people were not able to receive Geo on their television sets," says Azhar Abbas, director of Geo News. "After inquiries, our sources told us that the order had come from President Zardari." The Zardari government has been increasingly critical of what some of its members allege is an "orchestrated campaign" against them. In the lead-up to the long march, Geo and other channels endlessly taunted the government with footage of its election promises to restore Iftikhar Chaudhry, the chief justice sacked by Musharraf when he imposed the state of emergency. Once the crackdown began, there was blanket coverage of protesters being thrashed in the streets and hauled off to prison. Azhar Abbas denies that Geo News mounting a political campaign in favor of the lawyers and Sharif, who are demanding Chaudhry's immediate reinstatement. "What we were reminding them is that you yourself said these things, and now that you are in power you are not keeping your promises," he says of the government. "I think it the duty of journalists to remind politicians of their promises." Hours later, the government faced another setback when Sherry Rehman, a senior member of Zardari's Pakistan People's Party (PPP), resigned as Information Minister. Rehman had been a prominent campaigner for press freedom and had earlier vowed to resign if there was any move to muzzle journalists. Rehman's resignation is the latest sign of divisions in Zardari's ranks. Another senior minister, Raza Rabbani, resigned last week. And two former aides to Zardari's slain wife and former Prime Minister Benazir Bhutto, Naheed Khan and Safdar Abbasi, have launched fierce attacks on Zardari, accusing him of betraying Bhutto's legacy as they urged support for the antigovernment protests. Sharif has been singling out Zardari in his attacks, attempting to isolate the unpopular President from the rest of the PPP. The tactic appears to be paying off, with Zardari increasingly being seen as the chief aggressor. "The President is attacking every form of dissent," says Ayesha Siddiqa, a political and military analyst. "His very authoritarian behavior is raising a serious question: are we looking at Pakistan's Mr. Putin? And how does one deal with a President who breaks all promises?" Sensing opportunity, Sharif has cast himself as a man of principle and a victim of Zardari's excesses. Unburdened by the pressures of power, the Punjabi industrialist has been pushing the government to reinstate Chaudhry for over a year now. He quit the coalition government after Zardari backtracked on agreements to do so. A confrontation had been simmering over recent months, but broke into the open when the Supreme Court issued a controversial ruling last month barring Sharif and his younger brother, Shahbaz from standing for elected office. The ruling triggered the collapse of the younger Sharif's Punjab provincial government as Zardari moved swiftly to impose Governor's Rule, handing over control of the only province his coalition did not control to a key ally, Salmaan Taseer. The Sharifs have since been mounting public rallies, inflaming opposition to Zardari and gathering support for the long march. While he appears to have won popular support for the move, more discriminating observers believe that Sharif's calls for an independent judiciary are a tactic. Neither the PPP nor Sharif's Pakistan Muslim League-N (PML-N) have an attractive track record when it comes to the judiciary. Both parties stand accused of packing courts with pliable judges in search of favorable verdicts. In 1998, during his second term in office, Sharif's supporters stormed the Supreme Court when they feared a ruling against their leader. Critics of Zardari charge that he is unwilling to reinstate Chaudhry out of a fear that the independent-minded judge, who harried Musharraf's military rule in its last year, would revive corruption cases against the President. The government counters that Chaudhry has become "too politicized" and could paralyze their administration with his enthusiasm for judicial activism. But given the momentum generated by lawyers, Sharif supporters and other segments of the opposition and media, it is difficult to see how Zardari can forge a path out of this crisis without restoring Chaudhry to his old office. Moment after Clinton's phone calls to the two squabbling politicians, the government held out a peace offering to Sharif. It said it will now file a "review petition" in the Supreme Court, asking that it reconsider its order disqualifying the Sharifs from public office. But the Sharif camp has thus far refused to back down from its hardline position. And so, Pakistan's political crisis continues.