The accused movie theater shooter's defense made the offer Wednesday in a two-page filing. The document says the offer was also made prior to Holmes' arraignment, but the prosecution has not accepted because they may decide to seek the death penalty.
The offer would resolve the case with Holmes accepting life in prison without any opportunity for parole.
Holmes, a 25-year-old former University of Colorado graduate student in neuroscience, is charged with 166 counts in the July 20 massacre. The shooting, which occurred during a midnight showing of the "The Dark Knight Rises," left 12 moviegoers dead and injured 70 people.
Holmes' lawyers told the court they were not ready to enter a plea during a hearing on March 12, but Judge William Sylvester refused to wait and entered what he called the "standard" not guilty plea. That day, Sylvester told attorneys they could change the plea at a later date.
With the judge's entry of that plea on Holmes' behalf, a 60 day countdown began to the deadline for prosecutors to decide if they'll seek the death penalty.
"The only impediment to a resolution of this case would be if the prosecution chooses to seek the death penalty," the document says.
The recent defense filing suggests the case could be resolved as soon as Monday if the prosecution agrees not to pursue the death penalty.
"Mr. Holmes is currently willing to resolve the case to bring the proceedings to a speedy and definite conclusion for all involved," the document says.
The document also indicates, however, that the defense is continuing to explore a mental health defense and would use that if the case goes to trial.
A not guilty by reason of insanity plea carries risk. Prosecutors would gain access to Holmes' mental health records, which could help their case if the evidence of insanity is weak.
If Holmes does plead insanity, the proceedings would be prolonged further while he is evaluated by state mental health officials. With the judge entering the plea, prosecutors still don't have access to Holmes' health records.
If a jury were to agree he was insane at the time of the shooting, Holmes would be committed indefinitely to a state mental hospital. There would be a remote and unlikely chance he could be freed one day if doctors find his sanity has been restored.