A Nigerian court in Abuja is expected to hear Wednesday, a motion seeking to set aside the removal of the vice president by President Olusegun Obasanjo. Gilbert da Costa in Abuja reports Nigeria - which is on the verge of crucial elections - may be heading for a constitutional crisis.
The embattled vice president is optimistic that the Nigerian judiciary will annul his removal by President Obasanjo.
The president announced Abubakar's removal shortly after the vice president was nominated to run in next year's presidential election, on the ticket of the newly formed Action Congress Party.
The Action Congress has reacted angrily to the president's declaration and party spokesman Lai Mohammed says the opposition will, as he put it, resist the vice president's dismissal.
He said, "We are going to court; first, to exercise our fundamental human rights [on the basis of our constitution]. And, we have written letters to the CJN [Chief Justice of Nigeria] and the national assembly."
"And, we are meeting today - the board of trustees of the party - to examine the way forward. But one thing I can assure you is that we are not letting up. And, we believe that this kind of lawlessness and unconstitutionalism must be resisted," he added.
Several of Nigeria's leading lawyers have expressed worry over the rather arbitrary nature of the president's action, which was taken without recourse to the courts or national assembly, which has constitutional power to impeach the vice president.
Abuja-based lawyer Maxi Okwu says the president's conduct could set a very bad precedent, with grave consequences for the democratic process.
"My take on the legal position, as a lawyer of many years - the ways to remove a vice president or deputy governor or vice chairman of a local government, are very clearly stated. I therefore regard the dismissal or sacking of the vice president by the president as illegal and unconstitutional," he said.
"The danger is that, if it goes through, it will set a very bad example for Nigeria, because any day, any governor will wake up and sack his deputy and that could very dangerous for our democracy," he added.
Some analysts warn that - even if the vice president obtains a court order restoring him - the president may ignore the order, precipitating a possible constitutional crisis.
Abubakar had been Mr. Obasanjo's deputy since May 1999, but the two men fell out over an attempt by the president to seek a third term in office. Political tensions are rising ahead of crucial elections in April.