National leader John Key says there will be major changes to the bail laws if the party is re-elected.
Mr Key told an audience of senior citizens on the Kapiti Coast on Wednesday that National wants to target offenders with the highest risk of reoffending.
Instead of prosecutors having to prove that people accused of murder and class A drug offences are at risk of offending, absconding or interfering with witnesses or evidence, defendants would have to prove that they are not.
This burden of proof would be extended to those accused of violent and sexual offences who have a history of such offending.
Under National's policy, breaches of bail will be punishable by up to three months in prison in addition to the existing fine of up to $1000.
Young people who have previously served time in prison, or who repeatedly breach bail conditions, will also find it harder to get bail.
The proposed changes follow a review of the bail system by the Ministry of Justice.