According to the most recent poll British support for the EU membership has fallen by 2% to just 51%. On the contrary, support for leaving the European Union has increased by 2% to 43% during last week, little changed from figures published on April 19.
The results of the poll could suggest that U.S. President Barack Obama's words in favor of UK membership had yet to have an impact.
Several agencies and David Cameron's advisers are polling voters almost continuously regarding the referendum on June 23 on EU membership. The vote is crucial for the UK and the EU as well.
But, as Reuters reports, some have cast doubt on the results of the research, after the polling industry suffered a blow to its credibility last year when it failed to predict the Conservative Party's outright victory in a general election.
Meanwhile, continuing his European tour, Barack Obama visited Germany, to promote the Transatlantic Trade and Investment Partnership (TTIP) and the Trans-Pacific Partnership (TPP), which he believes will boost the American economy but has been under fire by both republicans and democrats, as well as abroad.
“Time is not on our side,” Obama told business leaders in Hanover. “If we don't complete negotiations this year, then upcoming political transitions in the United States and Europe would mean this agreement won't be finished for quite some time”.
Obama also discussed the situation in Syria and announced he would send 250 more troops to help local groups battling Islamic State.
He and Merkel also held huddled with Cameron, French President Francois Hollande and Italian Prime Minister Matteo Renzi on urgent issues including migration and renewed fighting between government forces and opposition groups.