The maximum jail sentence for stalking could be doubled to 10 years as part of a cross-party move to increase protection for women.
HuffPost UK understands that ministers are considering the move after the House of Lords voted to increase the current sentencing limit of five years.
The Government was defeated on Monday as peers passed a Policing and Crime Bill amendment, which was tabled by Labour’s Baroness Royall and supported by crossbenchers, Tories and Liberal Democrats.
With up to 16 Tory MPs having backed a Private Members’ Bill demanding a doubling of the sentence, the Ministry of Justice and Home Office are now facing a Commons defeat unless they back down on the issue.
In a significant move, Downing Street left open the possibility that the change could be accepted in the New Year when the amendment is next considered by MPs.
Asked if the Government would seek to overturn the Lords defeat or would instead consider adopting the amendment, the Prime Minister’s spokesman said: “The fact that we introduced new stalking protections last week is an indication of just how seriously an issue this Government believes this to be.
“Clearly maximum sentences for offences are kept under review. In terms of this amendment we will set out our response to that when the Bill comes back in front of the Commons.”
Tory MPs Alex Chalk and Richard Graham, whose private bill was incorporated by Labour in the Lords, are in talks with Government whips and ministers over the sentence plan.
The MPs told HuffPost UK they were having “constructive discussions with ministers” following the Lords vote.
Chalk, the MP for Cheltenham, and Graham, the MP for Gloucester, began their campaign to toughen the law on stalkers after a local GP, Dr Eleanor Aston, was stalked for eight years by former patient Raymond Knight.
In March 2015 Knight was sentenced to five years imprisonment, but the judge stated that he would have sentenced him to longer in prison if he could.
The National Stalking Helpline has already dealt with more than 3,550 calls this year.
Recent victims have included pop star Lily Allen, online campaigner Caroline Criado-Perez and Labour MP Stella Creasy. Tory MPs such as Nadine Dorries and Philip Davies have experienced stalker threats too.
Allen told this year of her seven-year ordeal at the hands of obsessive Alex Gray, who was eventually sectioned under mental health laws.
Campaign group Paladin produced a report last year which found that “light touch sentences” meant only 11% of stalkers received an immediate custodial sentence for offences.
The group hopes that Theresa May, who led the way at the Home Office in making stalking a priority issue and who has called it a “dreadful crime”, will use the Lords vote to seize the initiative on women’s safety.
One in five women and one in ten men will experience stalking in their lifetime according to Home Office statistics. A Metropolitan Police study found more than 40% of the victims of domestic homicide had been stalked.
Baroness Royall told HuffPost: “This was a great result but not the end of the road. I trust that ministers will now reflect on the seriousness of stalking and how it destroys lives, and then reconsider the government’s current position.
“I am very pleased to have had the support of Lord Hope, a former Deputy President of the Supreme Court whose views should be heeded.
“But if ministers try to overturn my amendment when the Bill goes back to the Commons, I hope they will be challenged by MPs from all sides. This is not about party politics but justice and saving lives, and I am glad to have worked with Conservative MPs like Alex Chalk and Richard Graham to get us this far.”