Liberal Democrat home affairs spokesman Max Wilkinson said the government “must deliver” on its promises and “get more officers back onto our streets”.
The reform plans would see police forces required to respond to emergencies in urban areas within 15 minutes, and within 20 minutes in rural areas.
Most forces already have response targets, but the Home Office said there was currently no way of holding them accountable if they do not meet that standard.
Failure to reach targets would see the home secretary sending in experts from high performing forces to help improve response times.
John Hayward-Cripps, chief executive of Neighbourhood Watch, said the new targets would be a “welcome step forward” towards the “basic expectation that police will respond when you report a crime”.
Mahmood will also say she wants to change how staffing levels are funded amid concern the current ‘officer maintenance grant’ encourages some forces to employ uniformed officers in administrative roles such as IT or human resources.