Chief Constable Sir Hugh Orde has said he does not want his officers to have to use plastic bullets again.
Sir Hugh stopped short of calling for a ban
Sir Hugh also acknowledged that some of the 14 people killed by plastic bullets during the Troubles were innocent.
Sir Hugh Orde's remarks come as Sinn Fein considers whether or not to proceed with a special ard fheis which could see it signed up policing.
In a wide-ranging interview, Sir Hugh stopped short of calling for a ban on plastic bullets.
He did not promise never to use the the modern version of the weapon.
He said that as chief constable he retained the right to use them - but stressed the best way of avoiding their use was for politicians to engage in policing.
Sir Hugh told the Press Association: "If the politicians do not secure a deal this time around, there are substantial implications for policing and substantial implications for the communities who these people are supposed to be representing.
"They need to realise that this is a huge opportunity that could move policing on, that could move confidence in policing on, and create conditions in Northern Ireland that move Northern Ireland on.
"Having now been allowed to officially meet Sinn Fein, my impression is the leadership is committed to joining policing but my impression also is they need to convince a lot of people in their community who are still unsure.
"That is one side of the equation. What is equally important is that other politicians in other parties help to create the space that allows the world to move on."
Responding to Sir Hugh's comment on plastic bullets, Sinn Fein Mitchel McLaughlin insisted there should be a total ban.
"Hugh Orde's acknowledgement of the hurt resulting from injuries and death of innocent people, including children, is also welcome.
"These weapons should never be used again."
The SDLP's Alex Attwood said it was disappointing that the police "continue to believe that they should be able to use plastic bullets".
"We must work for the day when something very different is being said about their use," he said.
However, he said it was "important to acknowledge that the use of force by the police has significantly reduced in the last five years".
Clara Reilly of the United Campaign Against Plastic Bullets said Sir Hugh's comments were "a very welcome and significant development".
"But this is only the first step in addressing the legacy of impunity that surrounds all of these killings. We now need the full truth about all of these killings," she said.