In the latest survey by Pew Research Center, 55% of Britons said they want to remain in the European Union (EU), while 36% wanted to leave.
The American think tank based in Washington said the British public's enthusiasm for leaving the EU has been declining since 2013, when they were evenly split on the issue, with 46% wanting to stay and 46% desiring to leave.
With the topic leading to a heated debated in political and policy circles, the UK intends to hold a referendum on continued membership in the European Union no later than the end of 2017.
Chancellor George Osborne has opened informal talks with European nations on how to rewrite the terms of Britain's place in the EU ahead of a proposed referendum on UK membership in 2017.
Most business leaders in Britain strongly oppose the prospect of the country leaving the EU, the biggest market for British goods, while international partners from the US to Germany and Ireland have made it clear they oppose a British EU exit and think it would isolate Britain.
Many Europeans had looked at the economic integration with doubt during the region's recession and currency crisis. However, the mood has changed, and favourable views of the EU and faith in a single, shared market are generally rebounding in the major EU member states, according to Pew Research.
In the survey of six nations – France, Germany, Italy, Poland, Spain and the UK – a median of 61% say they have a favourable opinion of the Brussels-based institution. This is up nine points among the same six countries in 2013.
Poles have the most positive view of the EU, with 72% of respondents supporting the union. The British have the lowest regard for the EU at 51%, but even that is up from its low point in 2013.