Documents released under the Freedom of Information Act (FIA) at the weekend reveal that in 2002, the US was also involved with those who briefly overthrew the democratically elected leader in a coup two years ago.
The million dollars of political funding were justified as an onging effort to build democracy and "strengthen political parties".
The revelation comes as the Venezuelan president faces a possible recall referendum and a series of violent street demonstrations in which at least eight people have died.
His opponents, who include politicians, some labour leaders, media executives and former managers at the state oil company, are trying to collect sufficient signatures to force a national vote.
Signatures and money
But FIA documents reveal that one of the group's organising the collection of signatures - Sumate - received $53,400 from the US in September 2003.
Jeremy Bigwood, a Washington-based freelance journalist who obtained the documents, said: "This repeats a pattern started in Nicaragua in the election of 1990 when [the US] spent $20 per voter to get rid of [the Sandinista President Daniel] Ortega.
"It's done in the name of democracy but it's rather hypocritical. Venezuela does have a democratically elected President who won the popular vote which is not the case with the US."
Hugo Chavez was democratically
elected, but not supported by US
The funding has been made by the National Endowment for Democracy (NED) a non-profit agency financed entirely by Congress.
It distributes $40m a year to various groups in what it says is an effort to strengthen democracy.
But critics of the NED say the organisation routinely meddles in other countries' affairs to support groups that believe in free enterprise, minimal government intervention in the economy and opposition to socialism in any form.
In recent years, the NED has channelled funds to the political opponents of the recently ousted Haitian president Jean-Bertrand Aristide at the same time that Washington was blocking loans to his government.
"It's the sort of stuff that used to be done by the CIA," said Bigwood. "I am not particularly interested in Chavez - I am interested in what Washington is doing."
In Venezuela, the NED channelled the money to three of its four main operational "wings".
The international arms of the Republican and Democratic parties - the International Republican Institute and the National Democratic Institute for International Affairs respectively - and the foreign policy wing of the AFL-CIO union, the American Centre for International Labour
"It's done in the name of democracy but it's rather hypocritical. Venezuela does have a democratically elected President who won the popular vote which is not the case with the US"
Washington-based journalist who obtained FIA documents
These groups ran workshops, training sessions and provided free advice to three political parties in Venezuela - Democratic Action, Copei and First Justice - the leaderships of which have been at the forefront of efforts to undermine Chavez.
Chris Sabatini, the director of the NED for Latin America, claimed the organisation's aim is to promote democracy and "build political space".
He told the New York Times that the endowment had been working with civic groups in Venezuela with no political ties and human rights groups.
Relations between the US and Venezuela have not been so tense since April 2002 when Chavez was briefly ousted by opponents who had been supported by the US in the run-up to the coup.
At the time, Washington blamed Chavez for his own downfall.
Washington's antipathy towards Chavez is fuelled by his friendship with Cuba's Fidel Castro and his open criticism of Washington-backed free market policies.
But Venezuela is also America's fourth largest supplier of oil - something that gives Chavez a degree of leverage but, at the same time, makes him vulnerable to those who would like to see a more pro-American leader in power.
In recent days, Caracas and other cities have been rocked by demonstrations in support of a national vote to force another general election.
Those intensified after the supposedly independent elections council ruled that government opponents lacked enough total signatures to force the vote.
There have also been large and vociferous marches by thousands of supporters of the president who oppose the vote.