Lawyers for Holmes said Wednesday he would plead guilty and serve the rest of his life in prison to avoid the death penalty.
The offer came days before the prosecution was to announce whether they would seek to have Holmes put to death if he is convicted for the attack that killed 12 people and injured 70.
"I think the issues around his sanity are going to be deeply debated and I would be wise to avoid pronouncing my own opinion about his sanity," said Gov. John Hickenlooper at the end of a trade mission to Alberta.
"Part of the challenge for all people is to separate your emotions from your judgment and I think that's what Colorado is trying to do right now. When you look at capital punishment...this is a hot topic in Colorado. Are we going to continue with capital punishment?"
Holmes, a former college student, is charged with 166 felony counts, mostly murder and attempted murder, in the July 20, 2012, attack during a showing of a Batman movie, in Aurora, Colo.
Prosecutors likely will consult with victims and their families before deciding whether to accept the offer.
Hickenlooper said he visited almost every family of the victims at the time of the shooting and most of them did not favour capital punishment.
"They were distraught, heartbroken, going through one of the most difficult events that anyone could imagine experiencing, but it was surprising even with the emotional intensity of that moment."