Conservative leader David Cameron said he wants the IRA to become an "old boys association".
Mr Cameron has visited Northern Ireland twice within a year
Mr Cameron, speaking during a visit to Northern Ireland, said he would prefer if "the IRA went away".
However, he said it "would be acceptable if they eventually became an old boys organisation".
During the Troubles, the IRA killed several Tory politicians and came close to killing Conservative leader Margaret Thatcher in Brighton in 1984.
Mr Cameron, on his second trip to Northern Ireland within a year, was speaking during a visit to the PSNI training college.
He went on to warn that Sinn Fein must not only join the Northern Ireland Policing Board but "must work fully with the PSNI".
Five people were killed in the Brighton bomb blast in 1984
Chief Constable Sir Hugh Orde and Mr Cameron held talks during which they discussed the row over the government's refusal to fully fund a new college outside Cookstown.
Asked afterwards if a Conservative government would provide the money, he said he could not make promises ahead of budgets and spending rounds.
Mr Cameron has also met the Institute of Directors and the sisters of murdered Belfast man Robert McCartney who are continuing a fight for justice.
He also met members of the Ulster Farmers Union which was highlighting its 'Cut it out' campaign.
Mr Cameron met members of the Ulster Farmers Union during his visit
UFA Chief Executive Clarke Black said: "We spoke to Mr Cameron about our campaign and the ridiculous level of bureaucracy which is weighing down farmers across Northern Ireland.
"During his speech, Mr Cameron highlighted the need to reduce government bureaucracy and as such we are delighted that he was in tune with our own feelings."
Mr Cameron's last visit to Northern Ireland was in December, a few days after he was elected leader when he pledged to promote the peace process.
BBC Northern Ireland political correspondent Gareth Gordon said: "Since then, the Northern Ireland Conservatives have had a renaissance of a kind with some defections from the Ulster Unionists.
"They say their membership here now stands at 350."