A coalition of opposition parties in Nicaragua has called on voters to boycott November's presidential poll, accusing incumbent President Ortega of trying to create a "dynastic dictatorship".
A coalition of opposition parties in Nicaragua has called on voters to boycott November's presidential poll.
A spokeswoman for the National Coalition for Democracy called it "fraudulent" and "a farce".
The opposition accuses incumbent President Daniel Ortega of trying to create a "dynastic dictatorship".
Polls suggest Mr Ortega is likely to win as the main opposition candidates have been barred from standing by the Supreme Court.
At a news conference, National Coalition for Democracy spokeswoman Violeta Granera said: "We herewith declare the absolute invalidity of these fraudulent elections and demand real elections."
She asked voters to abstain from voting altogether or to cast a blank vote.
She also accused Mr Ortega of wanting to create a family dynasty after he announced that he had chosen his wife Rosario Murillo as his running mate.
Critics have long accused the couple of running Nicaragua as their personal fiefdom.
The accuse President Ortega of using the Supreme Court to sideline his political rivals.
In a decision widely criticised as politically motivated, the court banned the leader of the main opposition party, Eduardo Montealegre, from his own party in June.
The man who replaced him as the Independent Liberal Party's presidential candidate, Luis Callejas, and his running mate, Violeta Granera, were also barred by the court from standing in the presidential poll.
Furthermore, Independent Liberal Party lawmakers were stripped of their seats in the National Assembly after they refused to recognise the party's new leader, who they say is close to Mr Ortega.
The move left the National Assembly entirely under the control of Mr Ortega's governing Sandinista Party and its allies.
President Ortega has also come in for criticism for his decision not to allow international election observers to monitor the 6 November polls.
He told observers to "put things in order in their own countries" and accused them of trying to gang up on his Sandinista Front party.
Supporters of the Sandinista Party say the opposition is hopelessly divided and point to Mr Ortega's previous election wins as signs for his continuing popularity.