KAMPALA, Uganda (AP) — On the eve of Uganda's presidential elections, Kampala resembles an armed camp with armored vehicles and police patrolling the capital city's streets.

President Yoweri Museveni, in power for 30 years, is facing his tightest race ever and appears to be responding with a show of military force in Kampala. His main challenger, Kizza Besigye, has run against Museveni four times and this time he has drawn large, enthusiastic crowds to his rallies despite some harassment by police. One of Besigye's supporters was killed and scores injured earlier on Monday as security forces dispersed a rally in Kampala.

Museveni, 71, remains popular in some parts of rural Uganda, where he is seen as a father figure and is beloved by those who remember his time as a guerrilla leader fighting a dictatorship. He came to power in 1986 and pulled Uganda out of years of chaos. Museveni is widely credited with restoring peace and presiding over economic growth. He is also a key U.S. ally on security matters, especially in Somalia, where Ugandan troops form part of an African Union force protecting the Somali government from Islamic extremists.

But some of Museveni's critics describe him as a dictator and accuse him of wanting to rule for life. Museveni has never said when he might retire, although his aides say there will be a smooth succession within the ruling party, the National Resistance Movement, when the time comes, and deny persistent accusations that Museveni is grooming his son — an army brigadier who commands the country's special forces — to succeed him.

Besigye, 59, served as Museveni's personal physician in the bush war and when the rebels came to power he became a minister in Museveni's cabinet and a colonel in the army. He broke away from Museveni in 1999, criticizing him for being authoritarian.

A recent poll, carried out by the group Ipsos, put Museveni's support at 53 percent. That survey, with a margin of error of plus or minus 2.2 percentage points, found that 28 percent of likely voters support Besigye. Some analysts say the race is tighter than what the poll indicates.

"I see a tightly contested race, if rigging does not happen," said Livingstone Sewanyana, who heads the local Foundation for Human Rights Initiative.

Uganda has more than 15 million registered voters, out of a population of 36 million. In Uganda a candidate needs more than 50 percent of the vote to be declared the winner.

Besigye told reporters Tuesday that the momentum is with him, citing the energy and enthusiasm of his supporters, some of whom have been showering him with cash gifts, farm animals and at least one sofa during lively campaign rallies. He is campaigning on a promise to run a more efficient government, and has vowed to stem official corruption, a key issue for some voters.

The potential for post-election "problems" is high if there is evidence of vote rigging, Besigye said, referring to the risk of people taking to the streets of Kampala and other cities.

Uganda has not had a peaceful transfer of power since independence from Britain in 1962.