Further delays to Nigeria's election are unacceptable and the opposition will take the government to court if the election commission chief is forced out, presidential candidate Muhammadu Buhari said Thursday.
The vote in Africa's largest economy pits incumbent Goodluck Jonathan of the PDP against former military ruler Buhari of the All Progressives Congress (APC) in the most hotly contested election since the end of military rule in 1999.
The vote was set for February 14 but postponed to March 28 after the Independent National Electoral Commission said it had been told by security chiefs they could not guarantee security due to an offensive against Islamist militant group Boko Haram.
"It is in our collective interest that the postponed elections will be held on the scheduled date, that they should be free and fair, and that their outcome should be respected by all parties," Buhari said in a speech in London.
"Any form of extensions under whatever guise is unconstitutional and will not be tolerated," he said.
The decision to postpone was widely viewed as the commission yielding to pressure by the the ruling party. Local media have reported mounting pressure on INEC chairman Attahiru Jega.
"Jega was appointed constitutionally," Buhari told reporters after giving his speech. "Let the president's supporters react [within] the constitution of the country. If they react unconstitutionally we'll take them to court."
The vote is another big test of security in Africa's most populous country, whose 170 million people are split almost evenly between Christian and Muslims. Eight hundred people died in violence after the last election in 2011.