The Prime Minister and the leader of the opposition came to blows over the UK's membership of the European Union in the House of Commons on 5 November.
Ed Miliband, speaking during Prime Minister's Questions, accused David Cameron of being a "don't know" Prime Minister after the Conservative Party leader pledged to make reforms to the EU's immigration policies.
But the plans came under threat after German Chancellor Angela Merkel reportedly said the move would lead to no "point of no return" for Britain and the country would exit the economic and political region.
"The Prime Minister is nearly two years into his renegotiation with the EU. He's got to get 27 countries to agree with him – how many has he got so far?" Miliband asked.
Cameron hit back at the Labour Party leader by arguing that the Conservative Party had a plan over the EU (offering an in-out referendum in 2017) and accused Miliband of being "frightened" of the British public.
"My position on the referendum is exactly the same as his was before he lost control of his party," the Labour leader retorted.
"If it's going so swimmingly [with Merkel], why does he think the Chancellor has already rejected his proposals?"
The Prime Minister argued that Miliband was "completely wrong" and claimed that the German leader had acknowledged that there were problems with the free movement of people principle in the EU that "need to be dealt with".
Cameron went on to cite Labour MP Alistair Darling's comments, that he thought an in-out referendum was "inevitable".
The exchange comes after a Lord Ashcroft poll put the Labour Party narrowly in the lead in key "battleground" seats ahead of the 2015 General Election.
The survey, which questioned more than 12,000 people in 12 Conservative-Labour constituencies found that Miliband's party led the Conservatives by 36% to 33% – a swing of 4.5% since the 2010 General Election.