HARARE, Zimbabwe — Zimbabweans are voting in elections that will determine the future of longtime President Robert Mugabe, who has denied allegations of vote-rigging despite concerns about the credibility of the polls.

Lines of voters snaked around a school in Harare, where polling booths opened just after the scheduled time of 7 a.m. Wednesday. Many were dressed in heavy coats to ward off the winter chill. Some had flasks of hot drinks.

Voter Isaac Rufaro says he joined the line before dawn, noting: "We have got to get this done."

The contest pits Mugabe against Prime Minister Morgan Tsvangirai, the former opposition leader who teamed up with the president's party in an uneasy coalition.

The power-sharing deal was forged by regional leaders after Zimbabwe's disputed and violent election in 2008.