Supporters of Gabon’s president and his chief rival have both said they expect to win an election that has proved to be the most serious challenge yet to the Bongo family’s half-century rule. The rival, Jean Ping, 73, traded accusations of fraud that raised the prospect of increased tension in the wake of an uncharacteristically bitter campaign. Ping distributed figures showing him easily beating incumbent Ali Bongo Ondimba in Saturday’s vote. “The general trends indicate we are the winner of this important presidential election,” Ping told reporters and a large crowd of cheering supporters gathered at his campaign headquarters in the capital, Libreville. “Despite numerous irregularities … you have managed to thwart this regime’s congenital traps of fraud.”