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By Deisy Buitrago
CARACAS, Feb 7 (Reuters) - Tens of thousands of Venezuelans streamed through the streets of Caracas on Saturday to protest leftist President Hugo Chavez's second attempt to change the constitution to let him govern as long as he wins elections.
Opinion polls gave a slight lead to Chavez before a Feb. 15 vote on whether to allow the president and other politicians to run for re-election as many times as they like in South America's top oil exporter.
Voters rejected a similar proposal in 2007.
The march, under the slogan "No is no" and led by anti-government students and political parties that say Chavez will turn Venezuela into a version of communist Cuba, was the largest by the opposition in more than a year.
"This reform hides, as President Chavez himself has said, the start of what would be a country, a state with a Castro-communist system," said Manuel Rosales, a former opposition presidential candidate.
If he loses, Chavez would leave office in four years, but he does not rule out trying again to change the electoral law.
Another referendum defeat for him could embolden opponents and increase resistance to unpopular spending cuts or a currency devaluation that analysts say might result if oil income stays low.
Chavez, a vocal critic of the United States, is close friends with ex-Cuban leader Fidel Castro and provides Cuba with cheap oil in return for doctors and advisers.
But Chavez denies he will prohibit private property and notes the government still works with foreign oil companies.
March organizers said hundreds of thousands of people took part, while government television said turnout was low.
"If we did a march, we would have 100 times the people they brought today," Chavez said during door-to-door campaigning in a poor Caracas neighborhood. He wore a baseball jersey with the word "Yes" emblazoned in red across his chest.
Protesters complained about a large rise in violent crime under Chavez and wore shirts emblazoned with the phrase "I also want to be president." Many carried Venezuela's red, yellow and blue flag in the march that stretched from the edge of the city's largest slum to a wealthy business district.
Chavez has nationalized industries and raised spending on health and welfare since he took office in 1999 but says he needs more time to build what he calls "21st century socialism" in one of the principal oil suppliers to the United States.
Still popular with about half of the population, he has amassed considerable power and most institutions are run by his allies. Opponents say Chavez is authoritarian and will turn people's homes and possessions over to the state.
Chavez has won multiple elections in the past decade and survived a brief coup, a months-long shutdown of the vital oil industry and a recall referendum.
Despite large street marches, the opposition only recently made gains against Chavez, defeating the 2007 referendum and winning seats in state and city elections last year.
Apparently confident of victory, Chavez has toned down his usually aggressive rhetoric against the opposition in recent days and said on Friday he welcomed the opposition march.
Despite a spate of police clashes with students, campaigning by both sides has been mainly low key. (Writing by Frank Jack Daniel; Editing by Peter Cooney)