The lawyers said Holmes would plead guilty to serve the rest of his life in prison in order to avoid the death penalty.
At a March 12 hearing, Holmes' attorneys told the judge they weren't ready to enter a plea. The judge then entered a not-guilty plea on Holmes' behalf.
Prosecutors were set to announce within days whether they would seek the death penalty for Homes for the July 20 attack that killed 12 people and injured 70.
Holmes is accused of meticulously planning the assault for months in advance. He allegedly entered a movie theater, threw a gas canister into the crowd and began shooting. He was arrested wearing ballistics gear and a police-style helmet outside the theater. Incendiary devices were found in his apartment, set to blow up if triggered by intruders, ostensibly investigating law-enforcement personnel.
Prosecutors did not say Wednesday whether to accept the potential plea. They will likely consult with victims and their families.
Defense attorneys said a mental health defense was still being considered.
Nearly eight months later, the defense has dropped hints about Holmes' mental state but has given no clear statement on whether he would plead insanity.
Holmes, a former graduate student at the University of Colorado, Denver, had seen a psychiatrist at the school before the shootings.
Last week, his lawyers revealed that he was taken to a hospital psychiatric ward in November because he was considered a threat to himself. Holmes was held there for several days and spent much of the time in restraints.
The judge scheduled the trial to start Aug. 5, setting aside four weeks.
The Associated Press contributed to this report.