Hassan was last among four candidates with 5 percent of the vote, but Imad insisted his poor showing wasn't the reason for his withdrawal. It was a major setback for a sitting president who has since seen his vice presidential candidate defect to support Nasheed.
The election controversy has sharply divided Maldivians, with Nasheed's supporters accusing the Supreme Court of colluding with the country's former autocratic leader Maumoon Abdul Gayoom.
The other two candidates and Hassan accuse the Elections Commission, which insists the first vote was free and fair, of favoring Nasheed.
Hassan, who was formerly vice president to Nasheed, became president last year when his predecessor resigned amid public protests and sliding support from the military and police over his decision to detain a top judge.