Al-Bashir has rejected the allegations and was defiant and dismissive a day before the court's decision was due.
"Any decision by the International Criminal Court has no value for us," he said on Tuesday, at an inauguration ceremony for a dam project on the Nile north of Khartoum, Sudan's capital.
"It will not be worth the ink it is written on."
Luis Moreno-Ocampo, the ICC prosecutor who called for an arrest warrant to be issued back in July last year, said he had strong evidence against the Sudanese leader.
"We have more than 30 different witnesses who will present how he managed and controlled everything," he said.
The ICC has no powers of enforcing its own arrest warrants, but suspects can be arrested on the territory of states who have signed up to the court's founding Rome Statute.
The UN says up to 300,000 people have died since conflict broke out in Sudan's western Darfur region in 2003, when ethnic minority fighters took up arms against Sudan's Arab-dominated administration for a greater share of resources and power.
Moreno-Ocampo accuses al-Bashir of personally instructing his forces to annihilate three ethnic groups - the Fur, the Masalit and the Zaghawa - and says about 2.5 million people have been victimised by his actions.
However, Al Jazeera's Mohammed Adow, reporting from Juba in south Sudan, said that it remained to be seen whether al-Bashir would ever appear before the court in The Hague even if the warrant is issued.
"It is almost impossible at the moment to think that Bashir would face eventually the ICC because at the moment his government is standing right behind him, and so are many of the Sudanese people, feeling a sense of unity beyond party lines and beyond political ideology," he said.
Hafiz Mohammed, a programme co-ordinator for rights group Justice Africa, told Al Jazeera that any arrest warrant would simply restrict al-Bashir's movements.
"He is not going to go out of Sudan ... because if he goes out of Sudan, there is a danger of being apprehended and handed over to the ICC. But I don't think the ICC have any mechanism by which they can enforce this decision," Mohammed said.
"That will have a very serious implication on the peace process and on the country as a whole because if you have an indicted president that means I am not expecting a foreign minister, or a prime minister or a president to go to Sudan and shake hands with him."
The UN's peacekeeping operations in Sudan have voiced concern that there could be violence in the country if an arrest warrant is issued.
Alain Le Roy, the head of UN peacekeeping operations, said that UN forces had undertaken "contingency planning to try to react to any situation", but said that he did not expect UN forces to be targeted.
The Justice and Equality Movement (Jem), Darfur's strongest rebel group, has threatened to refocus efforts to topple al-Bashir if a warrant is issued and he fails to co-operate.
"Bashir must go before the ICC, whether voluntarily or against his will," Khalil Ibrahim, the Jem head, said.
Ibrahim has also accused Sudan's government of planning riots if the ICC issues an arrest warrant.
The UN is also thought to be divided over the ICC's impending decision.
Ibrahim Dabbash, Libya's acting UN ambassador who is currently president of the UN Security Council, said that the council was not expected to have any immediate reaction to Wednesday's announcement by the tribunal's judges.
The Security Council has the power to suspend the ICC proceedings, but Dabbash said there were no plans for the body to meet if the court indicts al-Bashir.
The Arab League, African Union and the Organisation of the Islamic Conference have urged the council to stop the moves against al-Bashir, which they say will undermine the peace process in Darfur and could threaten the peace deal between north Sudan and the semi-autonomous south.
In May 2007, the ICC issued arrest warrants for Ahmad Harun, a Sudanese government minister, and Ali Kushayb, a leader of the Janjawid fighters, both accused of crimes in Darfur.
Khartoum has refused to honour those arrest warrants.
Moreno-Ocampo has also sought warrants for three so far unidentified Darfur rebel leaders in November last year over a deadly attack on African peacekeepers in 2007.