Rules to make sure there are enough nurses at work in hospitals should be extended to cover maternity and mental health wards, the Welsh Liberal Democrats are to say.
A law introduced by Welsh leader Kirsty Williams comes into force on Monday.
It means general hospital wards need a minimum number working at any one time.
Ms Williams will say the party’s manifesto for May’s assembly elections will contain a promise to extend the law.
As well as maternity and mental health wards, the party will also promise to extend the law to cover community nurses.
Speaking ahead of a visit to Cardiff’s University Hospital of Wales, Ms Williams said: “The Welsh Liberal Democrats have ensured that Wales becomes the first part of Europe with a legal duty for staffing levels.
“We will build on this success by extending the law to include mental health wards, maternity wards, and community nurses.
“In the forthcoming election, the Welsh Liberal Democrats will show that we have listened to people’s concerns.
“We all want NHS staff to have the time to care for our loved ones, which is why the Welsh Liberal Democrats will deliver safe staffing levels across the NHS.”