MANAGUA, Nicaragua — Nicaraguan opposition groups said Thursday that next month’s presidential election is “void and illegitimate” because of President Daniel Ortega’s arrests of critics and seven potential challengers.

A statement issued by the country’s main opposition alliances calls on the Organization of American States to suspend the Nicaraguan government from the body.

Ortega opened his election campaign this week almost unopposed, after he tossed most of his rivals in jail on treason charges. The opposition said those moves “ended any vestige of real electoral competition” in the Nov. 7 election, in which Ortega is seeking a fourth consecutive term.

The opposition statement was issued from Costa Rica, where many Nicaraguans have taken refuge amid the crackdown on politicians that began in May. It was signed by the Blue and White National Union, the Nicaraguan Democratic Front, the Democratic Renovation Union, the Farmworkers Union and other groups.

The statement accuses Ortega of holding 156 political prisoners in prison and “submitting them to torture, cruel and degrading treatment.” It also said about 140,000 Nicaraguans have had to flee their homeland since the government cracked down on widespread protests starting in 2018.

The statement calls on the OAS to “suspend the Ortega-Murillo dictatorship from the organization until real elections are carried out that comply with all standards and requirements.” That was a reference to Ortega’s wife and vice president, Rosario Murillo.

The statement also urges the European Union, the United Nations and individual countries to increase sanctions on the Ortega government. Both the United States and the EU have already imposed sanctions on Ortega and his allies, saying they are undermining democracy.

Ortega claims the anti-government protests that erupted in April 2018 were an attempted coup with foreign backing. And he has feuded with Catholic bishops who participated as mediators then in the short-lived first round of dialogue between the government and opposition, after which the government brutally put down the protests.

During one of his first campaign speeches this week, the president called the bishops “terrorists” and said many countries would have arrested them. He appeared to be referring to a pro-democracy plan submitted by Nicaragua’s council of bishops during those talks.

“The bishops signed that in the name of the terrorists, at the service of the Yankees … these bishops are also terrorists,” Ortega said in a broadcast. “In any other country in the world they would be on trial.”

Jailing bishops is far from idle talk for Ortega. At least seven opposition contenders have been jailed this year on vague treason charges. Ortega’s regime has also accused civic groups, opposition leaders and media outlets of everything from treason to money laundering.

At least 325 people died during clashes in 2018 between civilians and government forces in Nicaragua, while more than 52,000 people have fled the country, according to the Inter-American Commission on Human Rights.