Judges in England and Wales could be given greater discretion to decide the sentence tariffs for potentially dangerous criminals.
The Home Office is also expected to suggest ways to make sentencing guidelines clearer to the public.
It follows anger over the case of Craig Sweeney, who was told he could be released after five years of a life sentence for kidnap and sexual assault.
A consultation document is being published suggesting an overhaul.
Under rules introduced two years ago by then Home Secretary David Blunkett, non-violent offenders are automatically freed halfway through their sentences, to be supervised in the community by probation officers.
For those sentenced to life terms - apart from in murder cases - the "tariff" of time they must actually serve is arrived at by halving the equivalent determinate sentence.
In the Sweeney case, the 24-year-old offender - who kidnapped the child from her home in Rumney, in Cardiff, in January - had been given a sentence discount of one third for entering an early guilty plea.
His prison licence period for an attack on another child had run out just weeks before.
His minimum tariff was set in accordance with Home Office rules.
Following the case, Home Secretary John Reid pledged to examine whether judges should be given the power to dictate that serious offenders should serve longer in jail than the current guidelines allowed.
BBC home affairs correspondent Danny Shaw says the Home Office believes judges should no longer be required to apply the halving principle.
He says ministers also want to give courts greater powers to keep non-violent offenders in jail beyond the halfway point of their sentence if they might pose a risk to the public.
And the rules giving offenders who plead guilty early a third off their sentences are also being re-examined.
Our correspondent says the proposals will mean "major reform" of the Criminal Justice Act, which came into force just 18 months ago.
Speaking before Thursday's announcement, Paul Cavadino, chief executive of crime reduction charity Nacro, said: "Judges should have discretion over how much discount to give for a guilty plea."
But he said offenders who pleaded guilty early should continue to receive a greater discount than those who admitted their guilt at the 11th hour.
And he said automatic release under supervision after half of the sentence should be retained for the majority of prisoners.
Norman Brennan, director of the Victims of Crime Trust, said: "When someone has been sentenced to long-term imprisonment for committing a serious crime, it is these types of criminal that the public needs protecting from most.
"However with the judiciary being as liberal as they are I doubt very much whether many judges will overrule the automatic early release of prisoners.
"With the prison population being as over-crowded as it is, I think judges will look to that as being the over-riding factor."