Lagos, Nigeria(CNN) Nigerian President Muhammadu Buhari has come under intense scrutiny for suspending his country's Chief Justice just weeks before a general election, a move that critics have attacked as tyrannical and unconstitutional.
Buhari defended his decision on Twitter, saying corruption allegations against Chief Justice Walter Onnoghen -- who has been accused of failing to disclose bank accounts in foreign currencies -- are "grievous."
But the move was labelled a "coup against democracy" by the President of the Nigerian Senate, and prompted an outcry from the country's major opposition party, which halted its presidential election campaign temporarily in protest.
Describing the action as a "dangerous and brazen assault on the constitution," the Campaign Council of the opposition People's Democratic Party (PDP) said Friday that there was no point in campaigning in an election whose basis has been so flagrantly undermined.
"When democracy comes under this kind of virulent attack, then the election itself becomes superfluous," the statement said.
Buhari is seeking a second term as president in next month's elections, but his party has been accused of vote-buying by political opponents.
As the country's top judge, Onnoghen would have ruled on any legal challenge to the election.
That potential responsibility would now fall to Ibrahim Tanko Muhammad, whom Buhari swore in as acting Chief Justice of Nigeria (CJN) following his suspension of Onnoghen.
But many Nigerians have used social media to criticize Onnoghen's ousting, calling Buhari a tyrant and saying it's the President who should go.
They have been joined by numerous politicians from opposition parties, who have launched a cascade of condemnation against Buhari and urged him to reverse the decision.
"President Buhari has sent a dangerous signal to the entire world that Nigeria is no longer a democratic nation and that we have returned to the old, jaded era of military dictatorship," Senate President Bukola Saraki said in a statement, adding that he has "precipitated a constitutional crisis."
Chief Justice Onnoghen was charged on 12 January with breaching a rule that public officials disclose foreign bank accounts.
He had secured a temporary injunction to his hearing on Thursday, which seemingly prompted Buhari's move.
"One expected that with his moral authority so wounded, by these serious charges of corruption, more so by his own written admission, Mr. Justice Onnoghen would have acted swiftly to spare our Judicial Arm further disrepute by removing himself from superintending over it while his trial lasted," the President wrote on Twitter.
"Unfortunately, he has not done so," he wrote, adding: "If Justice cannot be done and clearly seen to be done, society itself is at risk of the most unimaginable chaos."
But the President's critics argued that due process had not been afforded to Onnoghen, and painted Buhari's move as a flagrant attempt to influence the outcome of the upcoming vote.
"This brazen dictatorial act is the latest action in the ongoing rape of our nation's hard earned democracy," PDP challenger and former Nigerian Vice President Atiku Abubakar wrote on Twitter.
"The case involving the legality or otherwise of the charges against Chief Justice Walter Onnoghen is in court, as it should be," he added. "Why not allow the court to adjudicate on the matter?"
The European Union (UN), which had been asked to observe the elections by the National Electoral Commission, said it was "very concerned" by the judge's suspension.
"The decision to suspend the Chief Justice has led to many Nigerians, including lawyers and civil society observer groups, to question whether due process was followed," a spokeswoman for the EU's Election Observation Mission said in a statement.
"The timing, just before the swearing in of justices for Electoral Tribunals and the hearing of election-related cases, has also raised concerns about the opportunity for electoral justice," she added.
The UK and US government in separate statements on Saturday also said Onnoghen's suspension could cast doubts on the credibility of the upcoming elections.
President Buhari dismissed concerns linking the judge's suspension to the elections.
Presidential spokesman Garba Shehu in a statement on Sunday said it was "illogical" for the countries to have linked the decision with the February vote, adding that the judge's refusal to recuse himself from his position during investigations prompted his suspension.
These countries would have taken the same action if faced with a similar situation, Shehu said in the statement.
"Not one of your nations would allow a person enmeshed in legal uncertainty to preside over your legal systems until the cloud has been cleared from him. That would incentivize corruption and assault the rule of law," Shehu said.
Nigeria's main opposition party People's Democratic Party said it had suspended its campaigns over the weekend in solidarity with the judge. It later resumed campaigning on Monday.
Next month's election is seen by many as a two-horse race between Buhari and Abubakar.
But Bring Back our Girls activist Oby Ezekwesili, who withdrew her candidacy on Thursday, promised to build a coalition capable of defeating both parties in order to "disrupt the politics of failure" in Africa's most populous nation.