Last month Maduro won a slim majority to continue the Bolivarian revolution legacy of Chavez, a populist firebrand who died of cancer in March.
Critics questioned the election, characterized widely as a succession orchestrated by Chavez, but were thwarted when the caretaker government under Maduro secured constitutional sanction and overall approval of the transition.
The opposition is adamant the election is invalid and has gone on to accuse Maduro aides of resorting to bribery, fraud and violence to secure power. It wants a new election for a proper transition from Chavez to a new president.
The critics further point out that Maduro's 1.5 percent scrape-through majority indicates the government's various ploys didn't work and that Venezuelans want radical change after 14 years of rule by mercurial rule by Chavez.
Oil-rich Venezuela is riven by industrial dislocation, social unrest and one of the world's worst homicide records.
Leading opposition challenger Henrique Capriles, who lost to Chavez by 11 percentage points in last October's election and to Maduro by 1.5 percent in April, called Maduro's election a fraud and cited multiple irregularities in the way he was chosen.
Capriles argued in the court challenge that "Chavezism" committed "electoral corruption, abuse of power and violent acts," prior, during and after the presidential election, El Universal newspaper reported on its website.
Capriles said the National Electoral Council "failed to prevent such wrongdoings."
The challenge seeks annulment of the vote and calls for a new election to choose the successor of Chavez.
The opposition's court action isn't assured of victory. The Venezuelan judiciary, including the Supreme Tribunal of Justice, is dominated by Chavez loyalists who are gradually transferring their allegiance to Maduro.
Analysts said the Supreme Court legal battle would likely be noisier than opposition protests over the outcome of the April snap election.
The legal challenge would also be a test for Maduro, who has indicated he wants to be a pragmatist and an efficient administrator of the country, a veiled contrast with the haphazard style of Chavez.
Support for the Chavez legacy remains strong and widespread among Venezuela's native population, socialist-backed middle class that benefited from Chavez's rule and the privileged Bolivarian aristocracy and government elite.
Criticism of inefficiencies that caused economic dislocation and discontent under Chavez is also palpable but muted.
Chavez lost popular approval on several occasions since coming to power in 1999 due to economic and social chaos caused by electricity shortages and blackouts, a wave of poorly managed nationalizations and poor management of oil revenues.
Opposition sources said the court challenge was a necessary step before the dispute is taken to the Inter-American Court of Human Rights, an institution shunned by Chavez and held in low esteem by Caracas.
Venezuela under Maduro continues to be suspicious of organizations with U.S. links. The Inter-American Court of Human Rights is an offshoot of the Organization of America States, which has headquarters in Washington.
Meanwhile, Maduro has indicated he has no intention of showing leniency toward detractors. Post-election protests and violence has already cost nine lives. Dozens more of protesters and police have been injured in riots since the April vote.
Opposition and pro-government lawmakers fought with their fists and their feet in a spectacular brawl in congress Tuesday. Maduro allies blamed the incident on provocation by opposition deputies.
The two sides also clashed during May Day marches.
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