COALITION SEEN
The other worry is rigging, which could prompt opposition parties to reject the result and call for street protests, raising concern over how the powerful army would react.
The country of 160 million people has alternated between civilian and army rule throughout its 60-year history.
Otherwise, a sympathy vote is expected to help Bhutto's Pakistan People's Party (PPP) become the largest party in the 342-seat National Assembly.
"Bhutto's mission is still alive, we will work for that," said Manzoor Ali, 60, voting with his wife and daughter in Bhutto's native district of Larkana in Sindh province.
Most analysts doubt the PPP can win a majority. Who it chooses for coalition partners will be vital to Musharraf.
Bhutto's widower, Asif Ali Zardari, who is co-chairman of the PPP, issued a conciliatory call for unity on the eve of the vote.
An alliance between the PPP and Sharif's party is what Musharraf dreads as Sharif is intent on bringing him down, perhaps through impeachment. Analysts say Musharraf wants a coalition between the PPP and the Pakistan Muslim League that backs him.
Western allies, who want a stable Pakistan to focus on fighting militancy, are hoping for a smooth vote, as are investors in a stock market that rose 40 percent last year but has shed about 3 percent since Bhutto's death.
International credit ratings agency Standard & Poor's said on Monday Pakistan was among several countries facing risks on account of political instability.
Nearly 81 million people are registered to vote. Several hundred foreigners, including a team of U.S. senators, and thousands of Pakistanis have fanned out to monitor the vote but are not allowed to do exit polls.
"We don't presume to suggest that by hitting several polling stations to know whether the poll is fair. All we can do is get a sense," U.S. Senator Joseph Biden told reporters in Lahore.
Biden has said the United States should cut military aid to Pakistan unless the election is credible but said unconditional economic assistance should be increased if it is fair.
