US Secretary of State Antony Blinken on Saturday said Nicaragua’s November election had "lost all credibility”, accusing President Daniel Ortega of an autocratic campaign to crush opponents.

Nicaragua’s electoral council on Friday disqualified the country’s main opposition party from the upcoming presidential polls, in an escalating political crackdown in the Central American country.

"The United States views the regime’s latest undemocratic, authoritarian actions — driven by Ortega’s fear of an electoral loss — as the final blow against Nicaragua’s prospects for a free and fair election later this year,” Blinken said in a statement.

"That electoral process, including its eventual results, has lost all credibility.”

The Supreme Electoral Council blocked the Citizen’s Alliance for Liberty (CXL) from participating in November 7 polls by ordering the "cancellation of the legal status” of the party, according to a court ruling.

Ortega, in power since 2007, is standing for a fourth consecutive term with his wife, Vice President Rosario Murillo, once again as his running mate.

At least 31 opposition figures, including seven potential presidential candidates, have been detained by authorities over the last two months.

They are accused of treason and threatening the country’s sovereignty under a law approved in December that has been denounced as a means of freezing out challengers to Ortega.

President for life? 

"President Daniel Ortega and Vice President Rosario Murillo’s decision on August 6 to ban the last genuine opposition party from participating in the November elections underscores their desire to remain in power at all costs,” Blinken said.

Ortega, a former left-wing guerrilla, governed Nicaragua from 1979 to 1990 when the United States backed armed opposition to his Sandinista movement.

He was reelected president in 2007, and in 2014 pushed through a constitutional amendment that scrapped presidential term limits, opening the way for him to remain president for life.

The Supreme Electoral Council has until August 9 to validate or reject candidates proposed by parties and alliances standing in the elections.

The CXL said this week its candidate for the vice presidency, Berenice Quezada, was being held under house arrest without any justification.

The United States on Friday announced it would refuse visas to another 50 Nicaraguans linked to Ortega, expanding restrictions on more than 100 people including legislators and judges.

Ortega had tried to rebrand himself as a business-friendly pragmatist but Western nations and the opposition say he is increasingly turning into a dictator as he seeks a stranglehold on power.