Venezuelan election officials rejected a high-profile opposition leader's attempt to register as a candidate Monday for upcoming congressional elections.

Former congresswoman Maria Corina Machado announced that the National Elections Council had rejected her attempt to register to run in the Dec. 6 elections and called it a grotesque violation of her rights.

Machado is among the hard-line leaders who called for President Nicolas Maduro to resign last year and helped lead sometimes bloody street protests demanding an end to the South American country's socialist administration. The ruling party stripped her of her congressional seat amid the protests.

Machado has become one of the most visible faces of the opposition, continuing to lead protests against Maduro.

In July, elections officials barred her and a handful of other high-profile critics of the country's socialist administration from holding office. Officials say Machado failed to make required financial disclosures. The state prosecutor's office has also accused her of conspiring to assassinate Maduro, a charge she denies as ridiculous.

The December elections represent the opposition's best chance in years to deliver an electoral defeat to the 16-year-old socialist revolution ushered in by late President Hugo Chavez. Polls show the opposition leading strongly as Venezuelans tire of chronic shortages, crime and inflation.

On Monday, Machado introduced a substitute candidate for the seat she had hoped to win: Caracas sociology professor Isabel Pereira Pizani.

The opposition coalition says the government is attempting to clamp down on its candidates out of desperation. Opposition leaders have called for nationwide protests Saturday.