Momentum in Greece’s referendum appears to be shifting toward a “yes” vote on creditors’ demands, an opinion poll said although the gap between the two camps is minimal—suggesting Sunday’s outcome hangs in the balance.

A poll published Friday and commissioned by Bloomberg News also showed a virtual tie, with 43% of responders planning to vote ”no” while 42.5% backing “yes.” The survey, conducted by the University of Macedonia Research Institute of Applied Social and Economic Studies, asked of 1,042 people and had a 3% margin of error.