Evo Morales looks likely to secure the largest slice of the vote, but the peculiarities of Bolivia's electoral system mean that if he falls short of an absolute majority the office of President could be handed to one of his rivals, courtesy of a conservative National Congress. Morales' supporters in the peasant and union movements are sure to meet any attempt to cheat him of the Presidency with calls for large-scale protests, and there is good reason to take them seriously: in the last three years, popular protest has forced two right-wing Presidents from power. Bolivians know how to organise a demo.
Morales has run a populist left-wing campaign, arguing for the nationalisation of the burgeoning gas sector, an end to coca eradication programmes, and a less supine attitude toward the United States. The peasant leader is supported politically and financially by Venezuelan Presdient Hugo Chavez, and many people have tagged him as an advocate of a Bolivian incarnation of Venezuela's 'Bolivarian revolution'. There are certainly a number of intriguing similarities, but two factors rule out the possibility of a Morales-led government following the path Chavez has pursued in Venezuela.
In the first place, Bolivia is a far poorer society than Venezuela, and Morales will lack the oil revenues that have allowed Chavez to satisfy his supporters with increased spending on social programmes. In the second place, Bolivia's trade union movement is stronger and more militant than its counterpart in Venezuela, and is sure to pressure a Morales administration from the left, demanding not just increases in social spending but changes to the basic structures of Bolivian society. (In the aftermath of the overthrow of President de Lozada in 2003, Bolivia's trade union confederation went so far as to demand the creation of a workers' state and workers' control of the key parts of the economy.)
It is very likely, then, that a Morales administration will come under immense pressure from the left and the right. On the right, the country's capitalist class and its backers in the US will fiercely resist even relatively minor reforms that threaten slender profit margins and a fragile economy. On the left the unions and peasants' organisations will be pushing their own agendas aggressively. The sort of relatively peaceful, relatively gradual change that has been possible in Venezuela is very unlikely to occur in Bolivia. It is likely that a Morales government will very quickly be faced with the choice of betraying its core constituencies, or provoking the wrath of Bolivia's ruling class and its powerful backers. But don't take my word for it: check out Latin America expert Jorge Martin's detailed Marxist analysis here. For a wider backdrop, check out the BBC's excellent interactive political map of twelve Latin American countries here.