Zimbabwe’s opposition leader Nelson Chamisa, filed a court challenge against President Emmerson Mnangagwa’s election victory, he wrote on Twitter, a step that would delay Mnangagwa’s inauguration that had been planning for August, 12.

Under the constitution, a losing presidential candidate has seven days to challenge the result from when a winner is declared. The Constitutional Court must rule within 14 days and Mnangagwa’s inauguration would have to wait for the outcome of Chamisa’s challenge.

Earlier this month, Mnangagwa secured a comfortable victory, according to results from the Zimbabwe Electoral Commission, polling 2.46 million votes against 2.15 million for the 40-year-old Chamisa. The opposition said the result was rigged.