Updated

Tens of thousands of Venezuelans clad in red flooded the streets of the capital on Thursday, saying a referendum that would end term limits is the only way President Hugo Chavez can complete what he calls a socialist revolution.

Nearby, a few hundred opponents rallied in a square after the government denied their request to mount a giant march across the city, as they did last weekend. They have fought Chavez in a bitter struggle that culminates in Sunday's vote, which is expected to be close.

Supporters jumped and screamed as Chavez rode through the crowd atop a red truck. They danced to salsa music booming from sound trucks, then listened rapt as Chavez addressed them.

"I have four years left in government," he said to boos. But if the amendment is approved, he said, "the horizon will change for the rest of the century."

Gregoria Escalona, 21, said she has bought a house and fed her two children thanks to social programs Chavez put into place. She fears those programs will end if Chavez leaves office when his term expires in 2013, as the constitution currently requires.

"Thanks to him, we have everything," she said.

The referendum would remove all term limits for elected officials, meaning that if he keeps winning elections Chavez could remain in power for decades, as he has said he should.

Polls indicate the vote will be a squeaker.

Luis Vicente Leon, director of the independent Datanalisis polling firm, said support for Chavez's proposal has increased in recent weeks due to intense government campaigning — including Chavez's near-daily televised addresses and his month-old newspaper column, published three times a week.

Opponents say Chavez has illegally diverted huge amounts of government resources into the campaign, and complain the government has routinely denied them permission to stage rallies.

"It's an example of the political discrimination that we live through every day," said university student Veronica Brito, 20.

Some government employees complain of political pressure to attend marches and support the referendum. Several told The Associated Press they fear they will lose their jobs if they don't.

Chavez is widely popular, but narrowly lost a broader referendum that also would have removed term limits in December 2007.