Video report by ITV News Deputy Political Editor Chris Ship
Turkey joining the EU is not currently "remotely on the cards", David Cameron has said.
The prime minister also told ITV's Peston on Sunday the EU referendum was more important than a general election.
Mr Cameron attacked Armed Forces Minister and Leave campaigner Penny Mordaunt after she said that it's "very likely" Turkey will join the EU in the next eight years.
Mr Cameron said he "wanted to make it very clear" Britain has a veto on another country joining the EU.
He added: "Turkey joining the EU is not remotely on the cards. At the current rate of progress it would be decades, literally decades, before this even had a prospect of happening. And even at that stage, we would be able to say no."
As the increasingly bitter clashes between the Remain and Leave camps fuelled divisions within the Conservatives, Mr Cameron insisted the party would "come back together".
"Of course this issue raises great passions. It is not surprising that you have people in a political party on either sides of the arguments," he said.
"I'm absolutely convinced that at the end of this the Government, the Conservative Party, will come back together and get on with the important job of running the country."
Asked if Boris Johnson's comparison between Adolf Hitler and the EU had made it impossible to give him a job in government, the Prime Minister told the programme: "I'm not going to get into jobs and the future now."
"Boris is hugely capable in lots of ways but I'm not going to go into Boris today," he added.