Most Tanzanians scrape by on the equivalent of a few dollars a day, so economic development is a pressing issue in the election, scheduled for Sunday. But corruption is a growing  and related  concern.

Mr. Kikwete’s ruling party has been widely accused of siphoning millions of dollars out of the treasury by awarding contracts to ghost companies. Perhaps no one in the campaign has better channeled voters’ frustrations over being poor while the ruling class is getting rich than Willibrod Slaa, a former Roman Catholic priest and legislator who has crusaded against corruption for years and is now running for president, along with five other challengers.

Tanzania’s government is not accustomed to upstarts. The governing party, the Party of the Revolution, was formed in the 1970s as a continuation of the Socialist-leaning political party that brought Tanganyika independence in 1961, and it has dominated Tanzanian politics ever since.

But the government now seems to be worried. It recently threatened to close independent newspapers, and Mr. Kikwete refused to debate Mr. Slaa on television, sending his campaign manager instead. The government is also delaying opening universities until after the election, which means many students will not be able to vote and will be scattered across the country, not concentrated on campuses, should there be any trouble.

Mr. Kikwete’s green guards, the governing party’s youth wing, have attacked journalists and opposition supporters. Tanzania’s police, who rarely confront civil disobedience, have tear-gassed rowdy opposition rallies. This is one of the few African countries that has escaped civil war and ethnic violence, but some Tanzanians now wonder if their tradition of harmony will be tarnished.