LUSAKA, Zambia (AP) — Zambia plans to hold elections on Aug. 11, replacing a president who took over last year after his predecessor died of illness while in office.

In a ceremony Tuesday, President Edgar Lungu is expected to approve a constitutional amendment ratifying the election date and requiring the winner of the presidential race to have more than 50 percent of the vote. Legislative elections will also be held.

The elections will pit the ruling Patriotic Front party against the opposition United Party for National Development, led by Hakainde Hichilema.

The struggling economy is likely to be a major campaign issue. Zambia's key copper industry has suffered, partly because of electricity shortages.

Lungu's predecessor, Michael Sata, died in 2014. Lungu was elected in January 2015 to serve out Sata's term until this year.