Jury selection begins this morning for Nichols, who is already serving a federal life sentence for the blast, which killed 168 people.
On Saturday, District Judge Steven Taylor scheduled a hearing for early Monday before jury selection begins. The nature of the hearing was not disclosed. Taylor scheduled the hearing a day after the FBI ordered a review of the bombing investigation to determine whether conspirator Timothy McVeigh may have had more accomplices.
Finding 12 jurors and six alternates for Nichols' jury could take up to two weeks and the trial itself could last more than three months. More than 150 prospective jurors will be present for the start of jury selection.
Defense attorneys have said they believe Nichols cannot receive a fair trial anywhere in Oklahoma.
Nichols' 1997 federal trial was moved to Denver because of extensive pretrial publicity. Last year, Taylor moved the state trial from Oklahoma City to McAlester, about 130 miles away, for the same reason.
Taylor, who will preside over Nichols' state trial, said in a pre-trial hearing last week he will seat an objective jury.
''I'm not going to sign off on a jury being fair and impartial until I'm satisfied,'' Taylor said. ''This is going to be a tedious, time-consuming process that is going to require the patience of jurors.''
A panel of 357 prospective jurors appeared for an orientation session a week ago. Taylor warned the panel that the trial could be long and might create personal hardships.
Nichols, 48, was convicted of federal involuntary manslaughter and conspiracy charges for the April 19, 1995, bombing of the Oklahoma City federal building.
He is serving a life sentence without parole for the deaths of eight federal law enforcement officers in the bombing. In Oklahoma, Nichols faces 161 counts of first-degree murder for the deaths of the other 160 victims and the unborn child of one victim.
State prosecutors are seeking the death penalty.
They allege that Nichols conspired with McVeigh to build a 4,000-pound bomb of ammonium nitrate and fuel oil that destroyed the Alfred P. Murrah Federal Building in a twisted plot to avenge the FBI siege at Waco, Texas, two years earlier.
McVeigh was convicted on federal murder charges and executed in 2001.
State charges were filed against Nichols in 1999 but there have been numerous delays while attorneys haggled over a series of issues ranging from defense attorney compensation to arguments that a state trial would be unconstitutional given his federal conviction.
Nichols' defense will rely on evidence of a wider conspiracy in the bombing. Defense attorneys believe Nichols was set up by unknown coconspirators to take the blame for the bombing.
Questionnaires filled out by prospective jurors sought personal and employment information as well as reading and television viewing habits, information about civic and religious organizations they belong to and whether they ever served in the military or law enforcement.
The questionnaire was developed to find out how much prospective jurors may know about Nichols and whether they have an opinion about his guilt or innocence.
Those issues, as well as views about the death penalty, will play crucial roles in jury selection.
While general questions will be posed in open court, prospective jurors will be questioned privately about Nichols and the death penalty to avoid influencing the views of others.
Taylor said prosecution and defense attorneys will have an opportunity to question jurors, but that he will control the process.
''The reason I am going to control it is because I am responsible for it,'' he said. ''Sometimes I think I can do things better than anybody else. It's just kind of a strange quirk in my personality.''