VENEZUELA’S highest court blocked opposition attempts to carry out a legislative coup against socialist President Nicolas Maduro on Monday.

The right-wing Democratic Unity Roundtable (Mud) alliance had proposed a constitutional amendment cutting the length of presidential terms from six years to four.

Mr Maduro was elected in April 2013 following the death of his United Socialist Party (PSUV) predecessor Hugo Chavez, who had been re-elected to a third term of office the previous year.

The amendment would have prompted an election next spring, with the Mud hoping to repeat its victory in December’s national assembly elections, in which it won two-thirds of seats.

But the Supreme Tribunal of Justice’s seven-member constitutional chamber ruled that even if such an amendment were passed, it could not be applied retrospectively.

Judge Arcadio Delgado quoted article 24 of the 1999 constitution — drafted and introduced during Mr Chavez’s first year in office — on “absolute retroactivity.”

Changes “cannot take effect retroactively or be applied immediately,” he said.

The chamber’s statement also called the amendment undemocratic, saying: “To admit such an assumption would constitute an unquestionable break with the exercise of sovereignty set out in article five of the Magna Carta, since that would be ignoring the will of the people.”

The court rejected much of the historical precedent presented by the Mud in arguments for the constitutional change, including the 22nd amendment of the US Constitution, adopted in 1951, limiting presidential candidates to two terms of office.

The amendment is one of the three components of the Mud’s “roadmap” to regime change against Mr Maduro’s government.

The other two prongs are a presidential-recall referendum and street protests — in a possible repeat of 2014’s year-long “guarimba” riots that left 43 people dead.

The Mud began collecting the nearly four-million petition signatories — 20 per cent of the registered electorate — it needs to trigger a referendum two weeks ago.

An eventual vote would need not only an overall majority but more votes in favour than the 7.59 million Mr Maduro received in 2003. The Mud got 7.73 million votes in last year’s parliamentary election.

Mr Maduro appointed veteran campaigner and former teachers’ union Suma leader Aristobulo Isturiz as his vice-president in January in an apparent move to position him as a popular successor candidate.