Ghana’s Vice President Mahamudu Bawumia has conceded defeat a day after a tense presidential election, marking a historic political comeback for the opposition candidate, former leader John Mahama.

Bawumia said in his concession speech on Sunday morning that internally collated results showed that “Mahama has won the presidential election decisively,” ahead of a formal announcement by the electoral commission.

Bawumia said the opposition National Democratic Congress (NDC) party had also won the parliamentary election. He said he conceded “to avoid further tension and preserve the peace of our country.”

“I have since called H.E John Dramani Mahama to congratulate him as President-elect of the Republic of Ghana,” Bawumia said, adding that “the people have voted for change at this time, and we respect that decision with all humility.”

Opinion polls had predicted a first-round victory for Mahama amid widespread discontent over the country’s economy and a crisis over illegal gold mining.

Ghanaians have been railing against environmental degradation caused by unlicensed small-scale mining, a longstanding issue that has left large swathes of land pockmarked by pits and major rivers polluted.

Ghana is also grappling with its worst economic situation in decades as it reels from high inflation, youth unemployment, and a steep increase in the cost of living.

Bawumia, 61, a UK-trained economist who chaired the nation’s economic management team, faced criticism ahead of the elections over his handling of the struggling economy. On the campaign trail, Mahama also criticized him for saying little about the economy.

Mahama, 66, described the election as a “defining moment” for Ghana and vowed to “reset” the nation on a path “for good governance and accountability.”

He said Sunday he had received a “congratulatory call” from Bawumia, following his “emphatic victory.”