The biggest test of Asif Zardari, Benazir Bhutto’s widower and Pakistan’s new President, from the American and British point of view, is whether he will take on the Taleban and other Islamic militants. The anger rising in Pakistan at the military action by the United States on its western border may prompt him to be much less helpful than Britain and the US want.

It was little surprise that Zardari won Saturday’s secret poll of the national Parliament and four provincial assemblies. But the scale of his victory showed just how successful he has been in winning support in just a few months, from a point where he was floundering. He won 481 votes out of 702, far more than the 352 that he needed. In Sindh province, the Bhutto heartland, he won all 65 votes, but only 22 out of 65 in Punjab, the power base of his rival, Nawaz Sharif. Those are the immobile blocks of Pakistan’s politics; more significant, then, is that in the two other deeply troubled provinces, he did so well. In North West Frontier Province he won 56 of 65 votes, and in Balochistan he won 59 of 65.

His reputation as one of the most controversial and mistrusted figures in Pakistan’s politics, which he secured during his late wife’s two spells as prime minister, is still intact. Many Pakistanis regard him with suspicion and derision. But he has shown himself smart enough to get power, at least by appealing to the power-brokers of the assemblies, if not the country’s 165 million people. The question is now what he wants to do with it.

The violence surrounding the day of voting shows the dilemma he faces. On Saturday a bomb exploded near Peshawar, the capital of North West Frontier, killing at least 30. Peshawar used to mark the farthest edge of government before the wildness of the tribal areas, but in the past year terrorist attacks by Islamic militants have rocked it and challenged that control.

The bomb came after two attacks apparently by US forces very close to the Afghan-Pakistan border. The first was a US commando attack in South Waziristan, a tribal area of Pakistan, after which Islamabad made “a strong protest” to Washington, saying that it retained the right to retaliate. The second, soon afterwards, was a missile strike by an unmanned US aircraft that killed at least six people in a group of Afghan houses about half a mile from the Pakistan border.

For years the US has been lambasting Pakistan to try harder to shut down militant activity on the border, to prevent Taleban and Arab fighters using it as a base from which to attack American and Nato forces in Afghanistan. The question is whether Zardari, prompted by the economic and military aid that he will need, will agree to continue. He may well not, because the US incursions are stirring up such hostility, and because the militants are now so strong. It may now be impossible for any Pakistani leader to crack down on the Taleban within Pakistan, one former Musharraf official said this week, because their support is so widespread.

In January Pakistani forces tried. Directed by Pervez Musharraf, then President, they launched a fierce drive into South Waziristan, in pursuit of militants led by Baitullah Mehsud, the leader of the Taleban in Pakistan, who was believed by the US and the Musharraf government to have planned the assassination of Bhutto. But after several weeks, the Army managed to strike an informal deal with Mehsud, according to reports. He would not organise suicide attacks in Pakistan, in return for freedom to cross the border. Zardari has already struck a deal with some of the most hardline Islamic groups, reopening a madrassa that was shut after Musharraf’s assault last year on the extremists of the Red Mosque.

It would be wrong to assume that Zardari will go easy on militants just because of that one deal, however repellent. This is a man who has shown already that he takes each pact as it comes, and if he is guided by overarching principles, he has kept quiet about them.

The United States, and Britain behind it, will shower him with promises of aid if he does take on the extremists. But all the same, the temptation for any president will now be to preserve peace in Pakistan by deals with the Taleban, at the expense of the Nato effort in Afghanistan.

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