The United States on Thursday condemned the killing of a 2-year-old boy in Zimbabwe as a “senseless and horrific act” and warned that if the murder was politically motivated it would call into question the country’s commitment to a free and fair election next month.

The US Embassy statement came as Zimbabwe’s military-backed president and a youthful opposition leader registered for the July 30 elections, the first without former leader Robert Mugabe’s participation.

President Emmerson Mnangagwa, the 75-year-old former Mugabe ally who took power with the military’s help in November, faces a strong challenge from Nelson Chamisa, a 40-year-old who has energised the main opposition party.

The US statement warned against “a continuation of violence during this campaign season.” The US and others have indicated that a free and fair election is a key step toward lifting international sanctions on Zimbabwe.

Mnangagwa has condemned the killing of 2-year-old Professor Lumbe over the weekend by Zanu-PF activists.

He asked police to investigate and called on the public to “be peaceful at all times” as the election approaches.

A police spokesperson confirmed that the boy’s father was a local candidate with the National People’s Party, an opposition outfit fronted by former president Robert Mugabe and his wife Grace.