Venezuelan opposition candidate Henrique Capriles has drawn a huge crowd of supporters for his final campaign rally in the capital, Caracas.
Mr Capriles criticised President Hugo Chavez for what he called a long list of unfulfilled promises.
And he demanded justice for three opposition activists killed during a rally in Barinas state on Saturday.
Mr Chavez addressed large crowds in Zulia state, promising to deepen socialism after the 7 October election.
Tens of thousands of people thronged the streets of Caracas on Sunday to voice their support for Mr Capriles.
“I think this is the biggest rally Caracas has ever seen,” Mr Capriles said.
“Bolivar Avenue is too small for us,” he said, as referring to one of the city’s main streets.
He also paid tribute to the three men who had died at the weekend.
“Yesterday, sadly, violence took three lives, something that should never have happened,” Mr Capriles said, in his last major rally in the capital before the election.
“I want to tell their families, and those angels in heaven, that we are going to defeat violence on 7 October.”
The three were named as Antonio Valero, Omar Fernandez and Hector Rojas.
The opposition First Justice Party said a rally had been planned in Barinas, President Hugo Chavez’s home state, on Saturday but the road was blocked by government supporters.
When Mr Valero and Mr Fernandez left their car to try to gain access, they were fired on by gunmen inside a van, it said.
The third victim, Hector Rojas, was also shot and subsequently died of his injuries.
Justice Minister Tareck El Aissami said in a message on Twitter that a suspect in the killings had already been arrested.
‘No provocations’
Addressing tens of thousands of people in the town of Cabimas in western Zulia state, President Chavez said an election victory for the opposition would put the country back “at least 30 years”.
“I haven’t deceived you nor have I failed you,” he said.
Mr Chavez also said he regretted the three deaths in Barinas and called for calm.
“It’s not with violence that we face off. It’s with votes, ideas, peace, so let’s not fall into provocations,” he said.
There have been other incidents of violence on the campaign trail. Supporters of both candidates threw stones at each other earlier this month when Mr Capriles attempted to march through the city of Puerto Cabello.
And four people were injured in a shooting that erupted during a voting rehearsal at the beginning of September.
With violent crime a key concern for voters, the BBC’s Sarah Grainger, in Caracas, says there are fears that further violence could erupt in what has become Venezuela’s closest fought election in over a decade.
Mr Chavez, who has been in power since 1999, was diagnosed with cancer last year.
More than 30 opposition parties have backed Mr Capriles as a single candidate.