The political parties of the two leading candidates each accused the other of gaining an advantage from the delay.

A considerably lower turnout is almost certainly guaranteed. It is unlikely many voters who live far from their polling stations will be able to afford the time or money to make the trip again. But it is unclear which candidate that would benefit.

The leaders of Mr. Buhari’s party said Mr. Abubakar would gain an advantage from “a breather” and that his party had been “bent on discrediting this process the moment it realized it cannot make up the numbers to win this election.”

Mr. Abubakar accused the president of orchestrating the delay to suppress voter turnout.

“Their plan is to provoke the public, hoping for a negative reaction, and then use that as an excuse for further antidemocratic acts,” he said.

Yet both camps also urged supporters to be patient in the face of a delay that risks inflaming tensions in an already tense election.