Nigerian President Muhammadu Buhari suspended Chief Justice Walter Onnoghen just weeks before what’s set to be a tight presidential vote, in a move the main opposition party condemned as an “act of dictatorship.”

Buhari, 76, appointed Ibrahim Tanko Muhammad in an acting capacity, he said in a statement Friday. Onnoghen was put on trial last week by the Abuja-based Code of Conduct Tribunal for an allegedly false declaration of his assets. In addition to that charge, Buhari said the security agencies found “suspicious transactions running into millions of dollars” in Onnoghen’s personal accounts.

The president also defended the move by saying he’d been ordered by the CCT on Wednesday to suspend Onnoghen until the trial is over.

Buhari’s main challenger in Feb. 16 vote, Atiku Abubakar, a 72-year-old businessman and former vice president who’s running for the People’s Democratic Party, condemned the decision.

“Our country is falling apart under the leadership of President Buhari and it is time to stand up for democracy,” Abubakar said in a statement. “This act of desperation is geared towards affecting the outcome of the elections.”

The decision is particularly concerning because the results may be contested in the Supreme Court, according to Adedayo Ademuwagun, a Lagos-based analyst at the risk advisory group Songhai Advisory LLP.

“This is another one of a string of events that indicates that this election will not be credible and will be challenged no matter who emerges as the winner,” Ademuwagun said.

Opposition parties previously criticized Onnoghen’s case and called it an attempt by the government to intimidate the judiciary before the election.

“I just hope it’s not true,” said Paul Usoro, the president of the Nigerian Bar Association. “It’s a situation the Nigerian Bar Association cannot accept because there’s no constitutional basis for it.”

Nigeria’s Federal High Court on Tuesday declined the government’s request that Onnoghen be ordered to stand down.

“What the president has done is essentially a coup against the judiciary,” said Cheta Nwanze, an analyst at SBM Intelligence in Lagos, the commercial capital. “I believe the other arms of government will stand against it.”