According to the Gallup fresh poll Moon is set to receive 38 percent of votes, while Ahn is projected to gain 35 percent, Sputnik reported.
Ahn's voting intention figures have significantly increased during the last three weeks, which can be partially explained by his tough stance on North Korea.
In general, five candidates are set to participate in the election. Apart from Moon and Ahn, other hopefuls are South Gyeongsang Province Governor Hong Joon-pyo of the former ruling Liberty Korea Party, Yoo Seong-min of the conservative Bareun Party and Sim Sang-jung of the minor progressive Justice Party.
The South Korean snap presidential election scheduled for May 9 follows the impeachment of former President Park Geun-hye in March over her involvement in extorting money from the country’s conglomerates.