The British people are split 50-50 over whether to stay in the European Union, according to an opinion poll published by the research firm ORB, which also suggested U.S. President Barack Obama has not won over many voters with his call for the country not to leave the bloc.

The online poll of 2,082 people, carried out between Wednesday and Friday for the Independent, showed the balance shifting slightly toward the “Out” campaign when accounting for the likelihood of respondents to actually vote in the referendum in June. That weighting gave the “Out” campaign 51 percent of the vote against 49 percent for “In,” ORB said Friday.

To decide on a possible British exit, or Brexit, Britons will vote June 23 on whether to end the U.K.’s 43-year membership in the EU. Many opinion polls have shown the outcome is too close to call.

Supporters of the “In” campaign, which has been led by Prime Minister David Cameron, had hoped that support by Obama, during a visit to London last week, for Britain to stay in the EU would help their cause.

Obama stressed the importance to Washington of Britain remaining an influence in the bloc, but he also warned that the country would go “to the back of the queue” in trade talks with Washington in the event it left the EU.

ORB said 66 percent of respondents disagreed when asked whether Obama’s comments made them more likely to vote to stay in the EU, compared with 23 percent who agreed.

An ORB representative said the overall, unadjusted 50-50 percent split in voting intentions compared with a 51-49 percent advantage for “In” found in an online poll by the firm in March.