Hip-thrusting music blared from the truck as it wound up the hill but the dancers trailing in its wake, street kids recruited for the day, were flagging and wore glazed smiles.

For the promise of a hot meal and a couple of dollars they were trying to inject excitement into a candidate's campaign, but this corner of Port-au-Prince paid little heed to the election circus. In the fading dusk light, the posters on the truck were nearly invisible, and in any case few of those hunched under tarpaulin in roadside rubble bothered to look. The little parade disappeared into the gloom, the candidate's identity a mystery.

Is this to be the fate of Haiti's election on Sunday – a brief, incongruous spectacle which leaves the ruins unchanged? Telfort Benson, 24, speaking for a crowd of youths at a camp for displaced people in the Cite Soleil slum, had no doubt. "Vote or not, we'll still get a president who doesn't keep his promises."

The international community has billed the vote for a new president and nearly an entirely new legislature as crucial to Haiti. "Perhaps the most important elections in its history," said the Brussels-based International Crisis Group thinktank.

They certainly ought to be. A country weighed by poverty has all but collapsed since January's earthquake. Now cholera is raging. Such momentous problems cry out for inspired leadership to tackle issues such as land ownership which have paralysed reconstruction.

With donors poised to pump in billions of dollars in aid the new government and congress should have significant resources – a gilded opportunity, as Bill Clinton, the UN's envoy has said, "to build back better". An eclectic collection of 19 candidates for "preziden" has plastered the country with billboards, posters and slogans in creole like "Tranay la poko fini" (The job is not done yet).

Opinion polls are notoriously unreliable but frontrunners include Jude Celestin, a technocrat, Mirlande Manigat, a university professor, and Michel Martelly, a musician and political outsider known for his cross-dressing and satirical lyrics.

If no one wins more than 50% there will be a run-off in January. Candidates for the 99-seat chamber of deputies and 11 seats in the 30-member senate are also running. With few voters having access to radio, TV or newspapers, campaigning means mounting speakers on trucks and blasting out kompa music and promises of better times ahead.

The camps and slums of Port-au-Prince seem underwhelmed. "I think it's very important to vote but not many here feel that way," said Michel Celestin, 37, leader of Crist Vivant, a collection of shacks and tents by the aptly named Gloup canal. "People don't feel motivated." Privately officials from the EU and UN fret that turnout among the 4.5 million eligible voters will slump below 40%, undermining the new government's mandate and extending chronic political instability.

Some observers want the vote delayed but that would create a dangerous vacuum, said the officials. Lack of enthusiasm partly stems from the wearying daily scrabble for clean water, decent food and dignity. In the capital some 1.5m are homeless. Unemployment is estimated at 90%.

Many lost identity documents in the earthquake and cannot vote. Those who can wonder if it is wise to do so during the cholera outbreak. The disease is not spread by person-to-person contact and there will be hand sanitisers at polling stations, but with more than 1,300 dead, and widespread ignorance about the bacteria's transmission, queuing with strangers does not appeal.

Another reason to stay away is resentment that the Fanmi Lavalas party of the ousted president, Jean-Bertrand Aristide, was banned from participating by the Provisional Electoral Council, which is perceived as a tool of President Rene Preval, who cannot run again but is promoting Celestin as a successor.

Wyclef Jean, the US-based Haitian hip-hop artist, was among 15 barred candidates. He retaliated with a song, Election Time, criticising Preval and calling for electoral officials to be jailed.

Exclusion as well as fraud allegations, said the advocacy group Institute for Justice and Democracy in Haiti, had removed the poll's legitimacy before a single ballot was cast.

Apathy also stems from the fact that whoever inherits the palace will be beholden to donors who provide 70% of the budget. "Once in power you become prisoner of the international community if you want assistance," said Robert Fatton, a Haitian-born politics professor at the University of Virgina. "Whoever wins will face the same constraints, though some people may negotiate the terms of Haiti's dependency better than others."

In the plaza at Champs de Mars a statue of Henri Christophe, a revolutionary general who bested Napoleon's army and helped make the Caribbean nation a proud black republic in 1804, still sat atop his horse. The plinth's marble reliefs show slaves breaking their chains.

Around the base, however, squatters who have made the area home complained they were too poor to send children to school or resume pre-quake jobs of selling fried vegetables. "In these circumstances it's not easy," said Jania Voltaire, 19, indicating a mound of fetid rubbish as she braided a neighbour's hair. "But no matter what happens, no matter who wins the election, I'm still very proud to be Haitian."

The presidential frontrunners

1 Mirlande Manigat, 70, a Sorbonne-educated university professor and former first lady who has championed education as Haiti's ticket out of misery.

2 Jude Celestin, 48, an engineer and former head of a state-owned road and bridge building company. The perceived favourite of some business elites and Preval, his campaign is well-resourced but tainted by the outgoing president's unpopularity.

3 Michel Martelly, 49, a well-known musician and Kompa entertainer who has styled himself the outsider who will clean out a corrupt elite. He has attracted large crowds and scooped up support which would have gone to Wyclef Jean.

4 Jean-Henry Ceant, 54, a prominent lawyer backed by factions of the excluded Fanmi Lavalas party of the exiled president Bertrand Aristide, who remains popular. Commentators say he appears to have gained momentum in recent weeks.