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Markey said there is a good chance that the January 8 election in Pakistan would be postponed.
The government, particularly President Pervez Musharraf, had expressed concern about its capacity to hold violence-free elections.
"This is just another indication of what they are dealing with, and their lack of ability to control the situation even under what appeared to be a fairly tightly organised event," he said.
Many Pakistanis hold Musharraf and his government "accountable, or at least negligent for allowing this to happen," Markey said.
On whether he thought the US government would continue to support Musharraf, Markey said the former is divided on its support to the Pakistan president, but he had support in the circles that mattered most -- the White House, the vice-president's office, and top echelons of the defence and state departments.
"There is general consensus that while he is not perfect and his country has failed to do a lot of the things they most wanted him to do, he is still a partner," he said, adding, "This latest tragedy is likely to reinforce beliefs within those offices that Pakistan is a dangerous and messy place, potentially very unstable and fragile, and that they need to cling to Musharraf even more than they did in the past."
There are other parts of the US government -- particularly those who have seen the Pakistani influence in Afghanistan and others who are sceptical of Musharraf's intentions -- that will continue to do so, Markey said.
"Probably not to the extent that they would believe he manufactured this latest crisis, but they would see he is still not a useful guy to work with," he observed.
The January election is important because it would allow the US to engage with a civilian government and not just Musharraf, who remains deeply unpopular in his country.
Bhutto being prime minister in the new government was often seen as a foregone conclusion, but if her party had won 30 or 40 per cent of the national vote, she would have been tremendously powerful -- the power behind the scenes if not the prime minister, Markey said.
A question that remains to be answered is who would be Bhutto's successor. The Pakistan People's Party leader has not anointed a successor, and that leaves the party vulnerable to jockeying or, in the worst case, disintegration.
Her husband Asif Ali Zardari has money, which puts him in an important position. However, he is said to be corrupt and has no broad political following of his own to be the leader.
Markey said it is tragic that Bhutto sidelined the most charismatic and effective among her party leaders because she considered them a threat. Aftab Ahmed Khan Sherpao, head of the PPP-S, the faction that split from the party, and Aitzaz Ahsan, PPP leader who represented Pakistan chief justice Iftikhar Chaudhry in court, are among those to watch in the days to come.
Sherpao, a former interior minister, survived a bomb attack during the Eid prayers on December 21.
If the PPP suffers a setback, other parties will benefit, and that includes Nawaz Sharif's Pakistan Muslim League-Nawaz. Sharif has announced that his party will boycott the election. But he will continue to be a power player, Markey said.
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