David Cameron has appealed to fellow European leaders to limit next year's EU budget to the "lowest possible" level.
The Prime Minister is expected to agree that the £107 billion budget will increase by at least 2.9% in 2011, despite previous British demands that it should not rise at all.
The UK's contribution could grow by more than £400 million, despite swingeing cuts across Whitehall.
But Mr Cameron has embarked on a round of telephone diplomacy to try to keep the rise to a minimum - and well below the 5.9% demanded by MEPs.
His conversations with German chancellor Angela Merkel, French president Nicolas Sarkozy and European Council president Herman Van Rompuy came ahead of a Brussels summit.
While the budget is not on the formal agenda, it will dominate conversations on the sidelines and in meetings between government heads and officials.
Mr Cameron - who will be attending his first EU summit as Prime Minister - has been calling for a freeze in the budget at a time when many countries, including the UK, are cutting spending.
The European Council has already agreed in principle a 2.9% increase, however, and British officials acknowledge that that is the minimum by which it will rise. The elected European Parliament is calling for a 5.9% rise. The final figure is likely to be somewhere in between and will set a baseline for the longer-term "financial perspective" which will determine the budget between 2014 and 2020.
Mr Cameron is trying to assemble a bloc of European leaders who can head off the MEPs' demands and ensure that the financial perspective is kept down. The Prime Minister also spoke to Swedish prime minister Fredrik Reinfeldt and Belgian prime minister Yves Leterme.
Minister for Europe David Lidington said the Prime Minister would be concentrating on trying to persuade fellow leaders of the importance of the budget issue. Mr Liddington told BBC Radio 4's Today programme: "What he's going to be focusing on is saying that whether it's 2011 or the more important long-term deal over the European budget, this is really something that deserves the highest priority among the leaders of all member states."