The government is doing “everything we can” to make sure rapist John Worboys stays in prison, Conservative party chairman Brandon Lewis has said.
The Parole Board has said ex-black cab driver Worboys, jailed in 2009 for assaults on 12 women, can be released.
But the government is considering challenging that decision in court.
Mr Lewis said it was crucial victims were “properly protected”, while a lawyer for victims said releasing Worboys would “put many women at risk”.
Justice Secretary David Gauke is looking into the possibility of applying for judicial review, but will only proceed if there is a good chance of success.
If a judge finds the Parole Board did not follow the correct process or reached its decision on the wrong basis, that decision would be quashed and Worboys would have to make a fresh application for parole.
Mr Lewis, who was appointed in the prime minister’s recent reshuffle, said he understood the public outrage at the decision to release Worboys.
Mr Gauke would be doing everything he could to make sure Worboys “stays behind bars”, Mr Lewis told BBC One’s Andrew Marr show.
Victims’ groups and representatives were outraged by news of Worboys’s imminent release earlier this month, saying many victims were not informed before it was made public.
Sarah Green, from the End Violence Against Women Coalition, said the justice secretary’s efforts were “very welcome”.
“Women have been singularly failed throughout this case, from initial investigations all the way through to the parole board decision,” she said.
She added that swift action was needed to review the risk Worboys poses to women’s safety and to “restore public confidence in the system’s ability to do justice and to protect”.
Labour MP Yvette Cooper tweeted that a legal review was needed, saying she had “deep, deep concerns” about the case after speaking to victims and their lawyers.
Analysis: A scoping exercise
By Alex Forsyth, BBC political correspondent
There was a huge backlash to the Parole Board’s decision to release John Worboys – from those who thought it was the wrong decision and from those who were critical about the way victims had been informed about it.
At this stage, David Gauke’s actions are just a scoping exercise, he won’t proceed unless he feels there are grounds to do so.
Nonetheless, this is significant. It is highly unusual for a justice secretary to intervene in the decisions of the Parole Board in this way, and that’s because the Parole Board is very deliberately independent of government.
It’s understood that Mr Gauke, who is new to the job of justice secretary, takes that independence very seriously and wants to maintain it, which is why at this stage he is just collecting information about the possibility of judicial review.
It comes after the Sunday Times reported that four cabinet ministers had warned Worboys’s release might be unlawful because victims were not consulted.
A Ministry of Justice spokesperson said: “Mr Gauke commissioned, mid-last week, advice on the plausibility of a judicial review and the prospect of success of any judicial review.
“The secretary of state is minded to move forward only if there was a reasonable prospect of success.”
The handling of Worboys’s release has already triggered a government review to look at how the Parole Board reaches its decisions.
Labour’s London Mayor Sadiq Khan said in a tweet that he was “astonished” by its decision, saying “it must listen to Worboys’s victims”.
“He should not be allowed to set foot in London,” he added.
At his trial, Croydon Crown Court heard Worboys gave his lone victims drug-laced champagne, saying he was celebrating a big lottery or casino win, before attacking them in his London taxi.
Harriet Wistrich, a lawyer representing one of the victims from Worboys’s criminal trial and another complainant, said she had also been looking into the possibility of judicial review.
Such a challenge would be unprecedented, she said, but at the very least her clients, who are both convinced Worboys remains a danger, deserve an explanation and an opportunity to be consulted.
The possible government intervention comes after the Crown Prosecution Service said it would not review the 93 cases that Worboys was not prosecuted over.
Parole Board chairman Nick Hardwick has said hearing the decision must have been “horrible” for the women, but the board was “confident” 60-year-old Worboys would not reoffend.
He said the fact some victims were not informed was a fault with the parole system, but the decision itself would have been carefully considered.