Scottish politicians have been outlining their views on the EU as the Prime Minister said he was "hopeful" of reaching a deal by February.
David Cameron said the in-out vote "would follow" if agreement with EU leaders was reached on his reforms.
The SNP's Stephen Gethins said Mr Cameron does not appear to have confidence in a renegotiation package.
Labour's Ian Murray said he was not aware of any Labour MSPs currently planning to campaign for an EU exit.
Meanwhile, Alex Johnstone of the Conservatives said Europe needs a "different sense of direction".
During an interview on the Andrew Marr programme, Mr Cameron also said he would stay on as PM even if he ended up on the losing side.
Stephen Gethins MP, the SNP's European affairs spokesperson, said: "The deep-seated divisions within the Tory party over Europe are becoming increasingly acrimonious and obvious ahead of David Cameron's EU referendum.
"The very fact that the Prime Minister is even entertaining the idea of a Brexit does not exactly show he is confident of securing a renegotiation package which will satisfy the Tory Eurosceptics .
"The SNP will make the positive case for Scotland and the UK's continued membership of the EU - but Scotland must not be dragged out of the EU against its will."
On Sunday Politics Scotland, Ian Murray - the Shadow Scottish Secretary and Labour's only MP in Scotland - said the "vast majority" of Labour members and supporters are pro-Europe.
He added: "We see the benefits of being part of the European Union. We are a broad church of a party. Both Scottish Labour and the UK Labour party will be campaigning and putting lots of resources behind staying within the European Union because we know it is in Scotland's interests to do so."
Mr Murray said that while it was apparent some Labour MPs would be campaigning in the referendum to leave Europe, he was currently unaware of any MSPs who intended to do so.
While the Scottish Labour Party will campaign to remain in Europe, individual MSPs will be given a free vote on the issue.
Mr Murray added Scottish Labour would share a platform with all parties campaigning to stay in the EU, but Labour would run its own distinct campaign.
Meanwhile, Mr Johnstone - a Conservative MSP who represents north east Scotland - told the programme he supports Mr Cameron's efforts to renegotiate Britain's membership of EU and he will vote in the referendum depending on how successful the Prime Minister is.
He said: "I think we have some serious problems in Europe at the moment. At this time, our direction in Europe is inappropriate."
Mr Johnstone believes the EU has not managed to deal with political problems generated by the refugee crisis, and the economic crisis in Greece and other smaller states.
'Dragged against our will'
He added: "Britain needs not to be dragged into that kind of situation against our will. I want a Europe that has a different sense of direction - one that is about opening up trade, opening up competition, opening up opportunity, not providing a political and economic straightjacket that will benefit some countries and disadvantage many more."
Ian Duncan is a Conservative MEP for Scotland. He said there has already been "substantial progress" in reforming the EU.
He told the programme: "There has been an 80% reduction in the laws passing through that particular chamber. That is because of Britain's pressure to do less, and to do less better."
Willie Rennie, the leader of the Scottish Liberal Democrats, said his party is united behind staying in the EU.
He added: "Despite his claims of commitment to it, David Cameron's sloping shoulders threaten the future of this country. By allowing UK government ministers to campaign against him instead of uniting behind him, the Prime Minister is only encouraging party infighting which will detract from the more important issues.
"The leader of the Scottish Conservatives needs to step up to the plate and show leadership in the way her Prime Minister is not. The EU has brought members states together, created peace, free trade and the ability for Scots to live, work and move around freely in Europe. We cannot put those liberties at risk."