Zimbabwe has extended voting in some wards by a day after polling stations failed to open on time on Wednesday, leading to protests by opposition candidates.

Voters in cities such as Harare and Bulawayo failed to cast their ballots on the first day of voting after election material were delivered late. These are often opposition strongholds and political leaders protested President Emmerson Mnangagwa’s ruling Zanu PF was trying to rig the polls.

President Mnangagwa’s main challenger, Nelson Chamisa of the Citizens Coalition for Change (CCC), said the incumbent was engaging “primitive” rigging tactics.

Read: Zimbabwe opposition fears skewed poll

The Zimbabwe Electoral Commission (Zec) said it had failed to print ballot papers on time because of a high number of court challenges against the nomination of some candidates.

Some decisions returned candidates to the contest weeks after Zec had refused to register them over lateness.

At most polling stations in Harare and Bulawayo, ballot papers were delivered late and ran out after a few hours.

Chamisa told journalists late on Wednesday that it did not make sense that polling stations in the capital did not have adequate election material yet voting in rural constituencies, considered to be Zanu PF strongholds, went on smoothly.

He said Zimbabwe was headed for a constitutional crisis because of another disputed election.

“They have no mandate to run this country, so they have plunged this country into a crisis,” Mr Chamisa said.

“Starting from Thursday, there is no government in Zimbabwe.

“Mr Mnangagwa can claim but he is not the president of this country, legally and constitutionally.”

Local election observers said there was a huge disparity of voting delays between urban centres and the rest of the country.

Read: Zimbabwe’s new elections facing familiar old fears

“While observers reported a relatively routine set up process in the polling stations that opened on time, the acute disparity of voting delays between urban centres and the rest of the country raises questions regarding voter equity and access,” read a state by the Zimbabwe Election Support Network and Election Resource Centre, who have the largest group of observers.

 Fabio Massino Castaldo, the head of the European Union observer mission, said their assessments showed that voting started late in at least 30 percent of the polling stations across Zimbabwe.

President Mnangagwa is being challenged by 10 other candidates, including Chamisa whom he narrowly beat in the disputed 2018 elections.

The opposition accuse the Zimbabwean ruler, who came into power in 2017 after a military coup that toppled strongman Robert Mugabe, of trying to steal the elections.

International observers complained that the Zimbabwean authorities did not clear them on time to follow their electoral processes while several local observers and journalists were barred from covering the polls.

Zimbabwe has a long history of disputed elections dating back to the Mugabe era.