The Swiss are likely to be called to vote on an initiative demanding an end to parole for criminals sentenced to life in prison. The initiative's supporters say prisoners serving life sentences should be denied the possibility of early release.
The vote will take place if the federal authorities validate at least 100,000 of the 196,000 signatures handed in on Wednesday.
About 100 people took part in a ceremony to hand in the signatures outside the federal parliament. They carried balloons inscribed with the slogan "For the protection of our children".
The signatures were collected by members of an organisation called Light of Hope. It members say criminals who have been judged extremely dangerous by psychologists should not be granted early release or let out on leave.
The initiative was launched after a number of prisoners, set free on parole, went on to commit murders.
swissinfo with agencies